Pub Date : 2024-07-05DOI: 10.3365/kjmm.2024.62.7.533
Seunghyeok Choi, Sang-Hwa Lee, Jae-Gil Jung, Seok-Jae Lee, Tae-Young Ahn, Yu-Song Choi, S. Son
Metal foam materials are used for various purposes including electrode materials, catalyst filters, and gas diffusion filters due to their porous structure. Increasing demand for metal foams has generated research to increase porosity as well as produce different pore sizes. The present paper illustrates a comparison of open-cell aluminum foams prepared using the space holder technique. The Al foams were fabricated by two different methods: spark plasma sintering (SPS) and the compression molding (CM) method. The effect of the content of sodium chloride particles, used as the space holder, as well as manufacturing technologies on the Al foam structure and their mechanical properties were investigated. The morphology and structure of the obtained Al foams were analyzed by scanning electron microscopy (SEM) and micro-computed tomography (CT). Compressive testing was performed to investigate mechanical properties. The porosity of the SPS Al foam sample was 61-74%, and was 60-72% for the CM sample. The compressive strength and Young’s modulus were 1.40 MPa, 1.41×10-2 GPa for the SPS sample and 0.9 MPa, 1.33×10-2 GPa for the CM sample, respectively. The space holder technique is a promising technique for fabricating metal foam materials for cathode current collectors in lithium-ion batteries applications.
{"title":"Investigation on the Structural and Mechanical Properties of Al Foam Manufactured by Spark Plasma Sintering and Compression Molding Methods","authors":"Seunghyeok Choi, Sang-Hwa Lee, Jae-Gil Jung, Seok-Jae Lee, Tae-Young Ahn, Yu-Song Choi, S. Son","doi":"10.3365/kjmm.2024.62.7.533","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.533","url":null,"abstract":"Metal foam materials are used for various purposes including electrode materials, catalyst filters, and gas diffusion filters due to their porous structure. Increasing demand for metal foams has generated research to increase porosity as well as produce different pore sizes. The present paper illustrates a comparison of open-cell aluminum foams prepared using the space holder technique. The Al foams were fabricated by two different methods: spark plasma sintering (SPS) and the compression molding (CM) method. The effect of the content of sodium chloride particles, used as the space holder, as well as manufacturing technologies on the Al foam structure and their mechanical properties were investigated. The morphology and structure of the obtained Al foams were analyzed by scanning electron microscopy (SEM) and micro-computed tomography (CT). Compressive testing was performed to investigate mechanical properties. The porosity of the SPS Al foam sample was 61-74%, and was 60-72% for the CM sample. The compressive strength and Young’s modulus were 1.40 MPa, 1.41×10-2 GPa for the SPS sample and 0.9 MPa, 1.33×10-2 GPa for the CM sample, respectively. The space holder technique is a promising technique for fabricating metal foam materials for cathode current collectors in lithium-ion batteries applications.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141674433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3365/kjmm.2024.62.7.503
Jae-Hyeon Park, Myung-Jin Kim, Heeshin Kang, Eun-Joon Chun
This study investigated the effect of a Ni-P coating layer on the solidification cracking behavior of Cu–mild steel dissimilar welds during the manufacturing of cylindrical Li-ion battery packs for electric vehicles. Four Cu plates were prepared and characterized: uncoated Cu and three levels (12, 50, and 100 μm) of Ni–P-coated Cu. The welding experiments used a single-mode fiber laser (2 kW) at extremely low heat input (1.82 J/mm) and high welding speed (1100 mm/s). Three laser beam patterns were used: linear, spiral, and wobble+spiral. Solidification cracking was detected for the Cu–Steel dissimilar welds for all the laser beam patterns on the uncoated Cu and the 50 and 100 μm Ni–P-coated Cu materials. Conversely, the dissimilar welds using 12 μm of Ni–P-coated Cu considerably suppressed solidification cracking behavior. Similarly, the welds with suppressed solidification cracking (using 12 μm of Ni–P-coated Cu) exhibited superior mechanical properties under the laser beam pattern. The weakest mechanical properties were confirmed for the welds using 100 μm of Ni–P-coated Cu. The solidification cracking and mechanical properties were highly dependent on the weld solidification of Ni and P. The suppression of solidification cracking in the welds using 12 μm of Ni–P coated Cu was attributed to the reduction in the weld mushy zone temperature range, due to the mixing of Ni, which reduced the solidification segregation of Cu. In contrast, the severe solidification cracking for the welds using 50 and 100 μm of Ni–P-coated Cu was estimated to result from the increased amount of incorporated P, which expands the weld mushy zone range.
{"title":"Effect of Ni-P Coating Layer on the Solidification Cracking of Cu-Steel Dissimilar Welds for Li-Ion Battery Pack Manufacturing","authors":"Jae-Hyeon Park, Myung-Jin Kim, Heeshin Kang, Eun-Joon Chun","doi":"10.3365/kjmm.2024.62.7.503","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.503","url":null,"abstract":"This study investigated the effect of a Ni-P coating layer on the solidification cracking behavior of Cu–mild steel dissimilar welds during the manufacturing of cylindrical Li-ion battery packs for electric vehicles. Four Cu plates were prepared and characterized: uncoated Cu and three levels (12, 50, and 100 μm) of Ni–P-coated Cu. The welding experiments used a single-mode fiber laser (2 kW) at extremely low heat input (1.82 J/mm) and high welding speed (1100 mm/s). Three laser beam patterns were used: linear, spiral, and wobble+spiral. Solidification cracking was detected for the Cu–Steel dissimilar welds for all the laser beam patterns on the uncoated Cu and the 50 and 100 μm Ni–P-coated Cu materials. Conversely, the dissimilar welds using 12 μm of Ni–P-coated Cu considerably suppressed solidification cracking behavior. Similarly, the welds with suppressed solidification cracking (using 12 μm of Ni–P-coated Cu) exhibited superior mechanical properties under the laser beam pattern. The weakest mechanical properties were confirmed for the welds using 100 μm of Ni–P-coated Cu. The solidification cracking and mechanical properties were highly dependent on the weld solidification of Ni and P. The suppression of solidification cracking in the welds using 12 μm of Ni–P coated Cu was attributed to the reduction in the weld mushy zone temperature range, due to the mixing of Ni, which reduced the solidification segregation of Cu. In contrast, the severe solidification cracking for the welds using 50 and 100 μm of Ni–P-coated Cu was estimated to result from the increased amount of incorporated P, which expands the weld mushy zone range.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141674875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3365/kjmm.2024.62.7.495
Gye-won Lee, Tae-jun Park, Seonung Choi, Jong-il Kim, Gye-seok An, In-hwan Lee, Yoon-seok Oh
In this study, we researched changes in the properties of a Thermal Barrier Coating depending on the powder structure. For this purpose, we used YSZ (Yttria Stabilized Zirconia), a commercial Thermal Barrier Coating material, to produce a powder with a Core-Shell structure. Bulk samples were prepared by hot pressing to analyze their properties according to the powder structure, and Thermal Barrier Coating samples were prepared by APS (Atmospheric Plasma Spray) to compare differences in properties according to the powder structure. The results of the bulk sample analysis showed that the thermal conductivity of YSZ was 3~4.2 W/m*K, the CeO2 mixed structure was 2.2~3.3 W/m*K, and the Core-Shell Composite was 2.2~2.9 W/m*K. The thermal Barrier Coating sample analysis showed that the TGO growth behavior was different depending on the powder structure. The YSZ coating sample was 7.24 µm, the YSZ+CeO2 coating sample was 6.68 µm, and the Core-Shell coating sample was 4.79 µm. In the case of high-temperature thermal conductivity, YSZ and YSZ+CeO2 showed similar results, but the Core-Shell coating sample had 79.07% thermal conductivity, compared to YSZ at 1000℃. These results indicate that the core-shell composite has improved thermal insulation performance and mechanical properties compared to YSZ, and it is expected that the core-shell composite will exhibit improved thermal properties compared to YSZ when applied to Thermal Barrier Coating.
{"title":"Core-shell Structured YSZ/CeO2 Composite Thermal Barrier Coating Fabrication and Properties","authors":"Gye-won Lee, Tae-jun Park, Seonung Choi, Jong-il Kim, Gye-seok An, In-hwan Lee, Yoon-seok Oh","doi":"10.3365/kjmm.2024.62.7.495","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.495","url":null,"abstract":"In this study, we researched changes in the properties of a Thermal Barrier Coating depending on the powder structure. For this purpose, we used YSZ (Yttria Stabilized Zirconia), a commercial Thermal Barrier Coating material, to produce a powder with a Core-Shell structure. Bulk samples were prepared by hot pressing to analyze their properties according to the powder structure, and Thermal Barrier Coating samples were prepared by APS (Atmospheric Plasma Spray) to compare differences in properties according to the powder structure. The results of the bulk sample analysis showed that the thermal conductivity of YSZ was 3~4.2 W/m*K, the CeO2 mixed structure was 2.2~3.3 W/m*K, and the Core-Shell Composite was 2.2~2.9 W/m*K. The thermal Barrier Coating sample analysis showed that the TGO growth behavior was different depending on the powder structure. The YSZ coating sample was 7.24 µm, the YSZ+CeO2 coating sample was 6.68 µm, and the Core-Shell coating sample was 4.79 µm. In the case of high-temperature thermal conductivity, YSZ and YSZ+CeO2 showed similar results, but the Core-Shell coating sample had 79.07% thermal conductivity, compared to YSZ at 1000℃. These results indicate that the core-shell composite has improved thermal insulation performance and mechanical properties compared to YSZ, and it is expected that the core-shell composite will exhibit improved thermal properties compared to YSZ when applied to Thermal Barrier Coating.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141676944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3365/kjmm.2024.62.7.524
Kyeonghun Kim, Jong-Goo Park, Haewoong Yang, Uro Heo, NamHyun Kang
The development and design of metal materials have been carried out through experimental method and simulation based on theoretic. Recently, with the widespread application of artificial intelligence (AI) in various fields, many studies have been actively incorporating artificial intelligence into the field of metal material design. Especially, many studies have been reported on adding rare-earth elements to aluminum alloys to improve corrosion resistance and mechanical properties using AI. However, the performance evaluation of artificial intelligence through experimental verification has not yet been reported related to metal material. In this study, we investigated the artificial intelligence algorithm capable of predicting the hardness based on the composition ratio of aluminum alloy with added Lanthanum (La) using experimental data and conducted a comparative analysis of the predicted hardness values. The machine learning models employed Adaptive Boosting Regressor (ADA), Gradient Boosting Regressor (GBR), Random Forest Regressor (RF), and Extra Trees Regressor (ET). The dataset comprised 1,210 encompassing 9 composition elements constituting the alloy. In the result, the findings revealed that the ET model demonstrated the most effective performance in predicting hardness. In addition, the microstructure became fine and showed the highest hardness at 0.5 wt.% La and hardness tended to decrease as the amount of La increased. The ET model showed excellent performance in predicting this tendency through experimental verification.
金属材料的开发和设计一直是通过实验方法和基于理论的模拟来进行的。近年来，随着人工智能（AI）在各个领域的广泛应用，许多研究也积极将人工智能融入金属材料设计领域。尤其是利用人工智能在铝合金中添加稀土元素以提高耐腐蚀性和机械性能的研究，更是屡见报端。然而，通过实验验证对人工智能进行性能评估的研究还未见与金属材料相关的报道。在本研究中，我们利用实验数据研究了能够根据添加镧（La）的铝合金的成分比预测硬度的人工智能算法，并对预测的硬度值进行了比较分析。机器学习模型采用了自适应提升回归器（ADA）、梯度提升回归器（GBR）、随机森林回归器（RF）和额外树回归器（ET）。数据集由 1210 个构成合金的 9 个成分元素组成。结果显示，ET 模型在预测硬度方面表现最为有效。此外，在 0.5 wt.% La 时，微观结构变得精细并显示出最高的硬度，随着 La 含量的增加，硬度呈下降趋势。通过实验验证，ET 模型在预测这一趋势方面表现出色。
{"title":"Aluminum Alloy Design by La Amount through Machine Learning and Experimental Verification","authors":"Kyeonghun Kim, Jong-Goo Park, Haewoong Yang, Uro Heo, NamHyun Kang","doi":"10.3365/kjmm.2024.62.7.524","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.524","url":null,"abstract":"The development and design of metal materials have been carried out through experimental method and simulation based on theoretic. Recently, with the widespread application of artificial intelligence (AI) in various fields, many studies have been actively incorporating artificial intelligence into the field of metal material design. Especially, many studies have been reported on adding rare-earth elements to aluminum alloys to improve corrosion resistance and mechanical properties using AI. However, the performance evaluation of artificial intelligence through experimental verification has not yet been reported related to metal material. In this study, we investigated the artificial intelligence algorithm capable of predicting the hardness based on the composition ratio of aluminum alloy with added Lanthanum (La) using experimental data and conducted a comparative analysis of the predicted hardness values. The machine learning models employed Adaptive Boosting Regressor (ADA), Gradient Boosting Regressor (GBR), Random Forest Regressor (RF), and Extra Trees Regressor (ET). The dataset comprised 1,210 encompassing 9 composition elements constituting the alloy. In the result, the findings revealed that the ET model demonstrated the most effective performance in predicting hardness. In addition, the microstructure became fine and showed the highest hardness at 0.5 wt.% La and hardness tended to decrease as the amount of La increased. The ET model showed excellent performance in predicting this tendency through experimental verification.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141676263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The stacking fault energy (SFE) of face-centered cubic (FCC) alloys is a critical parameter that controls microstructural and crystallographic texture evolution during deformation and annealing treatments. This review focuses on several FCC alloys, aluminum (Al), copper (Cu), austenitic stainless steels (ASSs), and high entropy alloys (HEAs), all of which exhibit varying SFEs. These alloys are often subjected to thermo-mechanical processing (TMP) to enhance their mechanical properties. TMP leads to the evolution of deformation-induced products, such as shear bands (SBs), strain-induced martensite (SIM), and mechanical/deformation twins (DTs) during plastic deformation, while also influencing crystallographic texture. High-medium SFE materials, such as Al and Cu, typically exhibit the evolution of Copper-type texture during room temperature rolling (RTR), while low SFE materials, such as ASSs and HEAs, display Brass-type texture at high reduction ratios. Moreover, the presence of second-phase particles/precipitates can also impact the microstructure and texture evolution in Al and Cu alloys. Particle-stimulated nucleation (PSN) during the annealing treatment has been reported for Al, Cu, ASSs, and HEAs, which causes texture weakening. Another interesting observation in severely deformed Cu alloys is the room-temperature softening phenomenon, which is discussed in the reviewed work. Additionally, plastic deformation and heat treatment of ASSs result in phase transformation, which was not observed in Al, Cu, or HEAs. Furthermore, the dependence of special boundaries in HEAs on plastic deformation temperature, strain rate, and annealing temperature is also discussed. Thus, this review comprehensively reports on the impact of TMP on microstructural and crystallographic texture evolution during plastic deformation and the annealing treatment of Al, Cu, ASSs, and HEAs FCC materials, using results obtained from electron microscopy.
面心立方（FCC）合金的堆积断层能（SFE）是控制变形和退火处理过程中微观结构和晶体纹理演变的关键参数。本综述重点讨论几种 FCC 合金、铝 (Al)、铜 (Cu)、奥氏体不锈钢 (ASS) 和高熵合金 (HEA)，它们都表现出不同的 SFE。这些合金通常需要进行热机械加工（TMP），以提高其机械性能。在塑性变形过程中，TMP 会导致变形诱导产物的演变，如剪切带 (SB)、应变诱导马氏体 (SIM) 和机械/变形孪晶 (DT)，同时还会影响结晶纹理。中高 SFE 材料（如铝和铜）在室温轧制 (RTR) 过程中通常表现出铜型纹理的演变，而低 SFE 材料（如 ASS 和 HEA）在高还原比时则表现出黄铜型纹理。此外，第二相颗粒/沉淀物的存在也会影响铝合金和铜合金的微观结构和纹理演变。据报道，铝、铜、ASS 和 HEA 在退火处理过程中的颗粒刺激成核（PSN）会导致纹理弱化。在严重变形的铜合金中观察到的另一个有趣现象是室温软化现象，这一点已在综述著作中进行了讨论。此外，ASS 的塑性变形和热处理会导致相变，这在 Al、Cu 或 HEA 中均未观察到。此外，还讨论了 HEA 中特殊边界对塑性变形温度、应变率和退火温度的依赖性。因此，本综述利用电子显微镜获得的结果，全面报告了 TMP 在铝催化裂化材料、铜催化裂化材料、ASS 催化裂化材料和 HEA 催化裂化材料的塑性变形和退火处理过程中对微观结构和晶体纹理演变的影响。
{"title":"Microstructure and Texture Evolution in Thermomechanically Processed FCC Metals and Alloys: a Review","authors":"Aman Gupta, Ranjeet Kumar, Lalit Kaushik, Sourabh Shukla, Vipin Tandon, Shi-Hoon Choi","doi":"10.3365/kjmm.2024.62.7.564","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.564","url":null,"abstract":"The stacking fault energy (SFE) of face-centered cubic (FCC) alloys is a critical parameter that controls microstructural and crystallographic texture evolution during deformation and annealing treatments. This review focuses on several FCC alloys, aluminum (Al), copper (Cu), austenitic stainless steels (ASSs), and high entropy alloys (HEAs), all of which exhibit varying SFEs. These alloys are often subjected to thermo-mechanical processing (TMP) to enhance their mechanical properties. TMP leads to the evolution of deformation-induced products, such as shear bands (SBs), strain-induced martensite (SIM), and mechanical/deformation twins (DTs) during plastic deformation, while also influencing crystallographic texture. High-medium SFE materials, such as Al and Cu, typically exhibit the evolution of Copper-type texture during room temperature rolling (RTR), while low SFE materials, such as ASSs and HEAs, display Brass-type texture at high reduction ratios. Moreover, the presence of second-phase particles/precipitates can also impact the microstructure and texture evolution in Al and Cu alloys. Particle-stimulated nucleation (PSN) during the annealing treatment has been reported for Al, Cu, ASSs, and HEAs, which causes texture weakening. Another interesting observation in severely deformed Cu alloys is the room-temperature softening phenomenon, which is discussed in the reviewed work. Additionally, plastic deformation and heat treatment of ASSs result in phase transformation, which was not observed in Al, Cu, or HEAs. Furthermore, the dependence of special boundaries in HEAs on plastic deformation temperature, strain rate, and annealing temperature is also discussed. Thus, this review comprehensively reports on the impact of TMP on microstructural and crystallographic texture evolution during plastic deformation and the annealing treatment of Al, Cu, ASSs, and HEAs FCC materials, using results obtained from electron microscopy.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141673742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3365/kjmm.2024.62.7.511
Hye-Min Lee, Jung Tak Moon, Young-Woo Lee, H. Kim, S. Lee, Joug-Hyun Lee
To form excellent solder joints in both thermal cycling and drop tests, Sn-2.5Ag-0.8Cu-0.05Ni-1Bi and Sn-0.75Cu-0.065Ni-1.5Bi composition solder balls were developed. In this study, undercooling and solidification characteristics of the alloys, resulting microstructural changes, the solid solution effect of Bi, physical properties, and interfacial reaction properties were investigated and compared with existing solder compositions of SAC305 and SAC1205N. The Sn-2.5Ag-0.8Cu-0.05Ni-1Bi and Sn-0.75Cu-0.065Ni-1.5Bi solders were found to have large undercooling of 38.36 ℃ and 33.38 ℃, respectively. As a result, the Sn-2.5Ag-0.8Cu-0.05Ni-1Bi solder ball had the smallest average size of Sn grains, and the eutectic structures between Sn grains formed relatively small areas and were observed to solidify into fine and uniform structures. Consequently, the total area of the β-Sn phase decreased, while the total area of the eutectic structure relatively increased. Using XRD and STEM analysis, we observed that the addition of a small amount of Bi resulted in a solid solution of the β-Sn phase, which increased the interplanar spacing of certain crystal planes, and contributed to the improvement in mechanical properties such as the hardness of the β-Sn phase. When using the Sn-2.5Ag-0.8Cu-0.05Ni-1Bi solder ball, the intermetallic compound (IMC) layer at the bottom Cu pad interface of the solder joint was relatively thin from right after reflow soldering and maintained a thin thickness throughout the thermal cycling test. The growth suppression property of the IMC layer by Sn-2.5Ag-0.8Cu-0.05Ni-1Bi composition was also confirmed in cases where the paste of this composition was applied to the existing solder ball.
{"title":"Solidification Behavior and Mechanical Properties of Sn-2.5Ag-0.8Cu-0.05Ni-1Bi and Sn-0.75Cu-0.065Ni-1.5Bi Solder Alloys, and Microstructures in Joints Formed Using Them","authors":"Hye-Min Lee, Jung Tak Moon, Young-Woo Lee, H. Kim, S. Lee, Joug-Hyun Lee","doi":"10.3365/kjmm.2024.62.7.511","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.511","url":null,"abstract":"To form excellent solder joints in both thermal cycling and drop tests, Sn-2.5Ag-0.8Cu-0.05Ni-1Bi and Sn-0.75Cu-0.065Ni-1.5Bi composition solder balls were developed. In this study, undercooling and solidification characteristics of the alloys, resulting microstructural changes, the solid solution effect of Bi, physical properties, and interfacial reaction properties were investigated and compared with existing solder compositions of SAC305 and SAC1205N. The Sn-2.5Ag-0.8Cu-0.05Ni-1Bi and Sn-0.75Cu-0.065Ni-1.5Bi solders were found to have large undercooling of 38.36 ℃ and 33.38 ℃, respectively. As a result, the Sn-2.5Ag-0.8Cu-0.05Ni-1Bi solder ball had the smallest average size of Sn grains, and the eutectic structures between Sn grains formed relatively small areas and were observed to solidify into fine and uniform structures. Consequently, the total area of the β-Sn phase decreased, while the total area of the eutectic structure relatively increased. Using XRD and STEM analysis, we observed that the addition of a small amount of Bi resulted in a solid solution of the β-Sn phase, which increased the interplanar spacing of certain crystal planes, and contributed to the improvement in mechanical properties such as the hardness of the β-Sn phase. When using the Sn-2.5Ag-0.8Cu-0.05Ni-1Bi solder ball, the intermetallic compound (IMC) layer at the bottom Cu pad interface of the solder joint was relatively thin from right after reflow soldering and maintained a thin thickness throughout the thermal cycling test. The growth suppression property of the IMC layer by Sn-2.5Ag-0.8Cu-0.05Ni-1Bi composition was also confirmed in cases where the paste of this composition was applied to the existing solder ball.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141673224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3365/kjmm.2024.62.7.550
Joonha Lee, H. Park, Junsu Kim, Won-Seon Seo, Sang-Il Kim, Hyun-Sik Kim
Bi2Te3 shows high thermoelectric performance near room temperature, making it the most widely used material in thermoelectric cooling applications. Cu doping has been found to be effective in improving the thermoelectric performance of Bi2Te3. However, due to the problem of easy migration of Cu ions, the stability of Cu-doped Bi2Te3 is always an issue, and therefore worth exploring. This study utilizes the Single Parabolic Band (SPB) model to analyze the electronic transport properties of CuxBi0.3Sb1.7-xTe3. We investigate how electronic band parameters (effective mass, non-degenerate mobility, weighted mobility, and B-factor) evolve with increasing Cu content (x). Additionally, the influence of electric current pulse (ECP) treatment is examined. Experimentally, the zT of x = 0.001 was higher than x = 0.0025 samples near room temperature. However, the SPB model predicts that due the higher B-factor of the x = 0.0025 sample, its theoretical maximum zT can be as high as ~1.48 at 350 K. Based on literature data on thermoelectric transport properties in the x = 0.001 sample after the ECP treatment, the impact of the ECP treatment on the electronic band parameters and the lattice thermal conductivity of the x = 0.0025 sample is estimated. ECP treatment slightly reduces electrical performance below 350 K, but it significantly suppresses the lattice thermal conductivity, ultimately leading to an enhanced zT. The predicted maximum zT reaches ~1.54 at 300 K.
Bi2Te3 在室温附近具有很高的热电性能，因此成为热电冷却应用中使用最广泛的材料。研究发现，掺杂铜可有效提高 Bi2Te3 的热电性能。然而，由于铜离子易迁移的问题，掺铜 Bi2Te3 的稳定性一直是个问题，因此值得探讨。本研究利用单抛物带 (SPB) 模型分析了 CuxBi0.3Sb1.7-xTe3 的电子传输特性。我们研究了电子能带参数（有效质量、非退化迁移率、加权迁移率和 B 因子）如何随着铜含量（x）的增加而演变。此外，我们还研究了电流脉冲（ECP）处理的影响。实验结果表明，x = 0.001 的 zT 高于接近室温的 x = 0.0025 样品。然而，根据 SPB 模型预测，由于 x = 0.0025 样品的 B 因子较高，其理论最大 zT 值在 350 K 时可高达 ~1.48。根据 ECP 处理后 x = 0.001 样品的热电传输特性的文献数据，估算了 ECP 处理对 x = 0.0025 样品的电子带参数和晶格热导率的影响。ECP 处理会略微降低 350 K 以下的电性能，但会显著抑制晶格热导率，最终导致 zT 增强。预测的最大 zT 在 300 K 时达到 ~1.54。
{"title":"Theoretical Maximum Thermoelectric Performance of Cu-doped and Electric Current Pulse-treated Bi-Sb-Te Alloys","authors":"Joonha Lee, H. Park, Junsu Kim, Won-Seon Seo, Sang-Il Kim, Hyun-Sik Kim","doi":"10.3365/kjmm.2024.62.7.550","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.550","url":null,"abstract":"Bi<sub>2</sub>Te<sub>3</sub> shows high thermoelectric performance near room temperature, making it the most widely used material in thermoelectric cooling applications. Cu doping has been found to be effective in improving the thermoelectric performance of Bi<sub>2</sub>Te<sub>3</sub>. However, due to the problem of easy migration of Cu ions, the stability of Cu-doped Bi<sub>2</sub>Te<sub>3</sub> is always an issue, and therefore worth exploring. This study utilizes the Single Parabolic Band (SPB) model to analyze the electronic transport properties of Cu<sub><i>x</i></sub>Bi<sub>0.3</sub>Sb<sub>1.7-<i>x</i></sub>Te<sub>3</sub>. We investigate how electronic band parameters (effective mass, non-degenerate mobility, weighted mobility, and <i>B</i>-factor) evolve with increasing Cu content (<i>x</i>). Additionally, the influence of electric current pulse (ECP) treatment is examined. Experimentally, the <i>zT</i> of <i>x</i> = 0.001 was higher than <i>x</i> = 0.0025 samples near room temperature. However, the SPB model predicts that due the higher <i>B</i>-factor of the <i>x</i> = 0.0025 sample, its theoretical maximum <i>zT</i> can be as high as ~1.48 at 350 K. Based on literature data on thermoelectric transport properties in the <i>x</i> = 0.001 sample after the ECP treatment, the impact of the ECP treatment on the electronic band parameters and the lattice thermal conductivity of the <i>x</i> = 0.0025 sample is estimated. ECP treatment slightly reduces electrical performance below 350 K, but it significantly suppresses the lattice thermal conductivity, ultimately leading to an enhanced <i>zT</i>. The predicted maximum <i>zT</i> reaches ~1.54 at 300 K.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141674355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3365/kjmm.2024.62.7.558
Geun-Hyoung Lee
SnO2 nano/micro-crystals with different morphologies were fabricated by the thermal evaporation of SnO2 powders mixed with Ga2O3 powder. The synthesis process was performed at 1300℃ in air. X-ray diffraction (XRD) analysis, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to examine the morphology, microstructure, elemental composition and chemical property of the as-synthesized products. X-ray diffraction analysis revealed that the products were SnO2 with a tetragonal rutile crystal structure. From the Fourier transform infrared spectra of the products, Sn-O stretching mode was observed, which confirmed the formation of SnO2. Scanning electron microscopic analysis clearly showed that the morphology of the SnO2 crystals was significantly affected by the addition of Ga2O3 to SnO2 source powder. SnO2 crystals with a belt-like morphology were grown when the source powder without Ga2O3 powder was used. Rod-like SnO2 crystals were grown by using SnO2 powder mixed with Ga2O3 powder as the source powder. When the amount of Ga2O3 mixed in the source powder was increased, the morphology of the SnO2 crystals changed from rod to tube. Energy dispersive X-ray analysis indicated that the inner core of the tube-like crystals was composed of Snrich metastable phase. No catalytic particles were observed at the tips of the SnO2 nano/micro-crystals, suggesting that the growth process occurred by vapor-solid growth mechanism.
{"title":"Effect of Ga on the Morphology of SnO2 Nano/Micro-Crystals Grown by a Thermal Evaporation Method","authors":"Geun-Hyoung Lee","doi":"10.3365/kjmm.2024.62.7.558","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.558","url":null,"abstract":"SnO<sub>2</sub> nano/micro-crystals with different morphologies were fabricated by the thermal evaporation of SnO<sub>2</sub> powders mixed with Ga<sub>2</sub>O<sub>3</sub> powder. The synthesis process was performed at 1300℃ in air. X-ray diffraction (XRD) analysis, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to examine the morphology, microstructure, elemental composition and chemical property of the as-synthesized products. X-ray diffraction analysis revealed that the products were SnO<sub>2</sub> with a tetragonal rutile crystal structure. From the Fourier transform infrared spectra of the products, Sn-O stretching mode was observed, which confirmed the formation of SnO<sub>2</sub>. Scanning electron microscopic analysis clearly showed that the morphology of the SnO<sub>2</sub> crystals was significantly affected by the addition of Ga<sub>2</sub>O<sub>3</sub> to SnO<sub>2</sub> source powder. SnO<sub>2</sub> crystals with a belt-like morphology were grown when the source powder without Ga<sub>2</sub>O<sub>3</sub> powder was used. Rod-like SnO<sub>2</sub> crystals were grown by using SnO<sub>2</sub> powder mixed with Ga<sub>2</sub>O<sub>3</sub> powder as the source powder. When the amount of Ga<sub>2</sub>O<sub>3</sub> mixed in the source powder was increased, the morphology of the SnO<sub>2</sub> crystals changed from rod to tube. Energy dispersive X-ray analysis indicated that the inner core of the tube-like crystals was composed of Snrich metastable phase. No catalytic particles were observed at the tips of the SnO<sub>2</sub> nano/micro-crystals, suggesting that the growth process occurred by vapor-solid growth mechanism.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141676367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-05DOI: 10.3365/kjmm.2024.62.7.542
Jin-Sol Kim, D. Shin, K. Park, Il-Ho Kim
Skutterudite compounds have excellent thermoelectric performance in the intermediate-to high temperature range. Their lattice thermal conductivity can be reduced by intensifying phonon scattering through independent vibrations of the guest atoms, by filling the voids within the lattice. Furthermore, the thermoelectric figure of merit (ZT) can be enhanced by optimizing the carrier concentration through charge compensation between transition elements. In this study, we compared the thermoelectric properties of p-type filled skutterudite materials, RyFe4-xCoxSb12, where R represents rare-earth elements (La/Ce/Pr/Nd/Yb), which were filled in the voids, and Co was charge-compensated at the Fe site. In the case of LayFe4-xCoxSb12, the introduction of La filling and Co doping led La0.9Fe3CoSb12 to exhibit a high power factor and low thermal conductivity (ZT = 0.67 at 723 K). In the case of CeyFe4-xCoxSb12, in addition to Ce filling, the substitution of Co for Fe resulted in additional lattice scattering, leading to a decrease in thermal conductivity. However, CeFe4Sb12 exhibited a maximum performance of ZT = 0.70 at 823 K. In the case of PryFe4-xCoxSb12, the thermal conductivity was reduced through phonon scattering induced by Pr filling and additional lattice scattering caused by Co substitution; as a result, Pr0.8Fe3CoSb12 exhibited ZT = 0.89 at 723 K. In the case of NdyFe4-xCoxSb12, the phonon scattering was enhanced by adjusting the filling of Nd and substitution of Co, resulting in a lower thermal conductivity; Nd0.9Fe3.5Co0.5Sb12 exhibited ZT = 0.91 at 723 K. For YbyFe4-xCoxSb12, Yb0.9Fe3CoSb12 exhibited a thermoelectric performance of ZT = 0.56 at 823 K. In addition, in this study, for the fabrication (application) of thermoelectric modules, the p-type Nd0.9Fe3.5Co0.5Sb12 skutterudite, which exhibited the best thermoelectric performance, was prepared in bulky compacts to verify the uniformity and reproducibility of its thermoelectric performance.
沸石化合物在中高温范围内具有出色的热电性能。通过填充晶格内的空隙，利用客体原子的独立振动加强声子散射，可以降低晶格热导率。此外，还可以通过过渡元素之间的电荷补偿优化载流子浓度，从而提高热电功勋值（ZT）。在本研究中，我们比较了 p 型填充矽卡岩材料 RyFe4-xCoxSb12 的热电性能，其中 R 代表稀土元素（La/Ce/Pr/Nd/Yb），填充在空隙中，Co 在 Fe 位点进行电荷补偿。就 LayFe4-xCoxSb12 而言，由于引入了 La 填充和 Co 掺杂，La0.9Fe3CoSb12 表现出较高的功率因数和较低的热导率（723 K 时 ZT = 0.67）。就 CeyFe4-xCoxSb12 而言，除了 Ce 填充外，用 Co 代替 Fe 还导致了额外的晶格散射，从而降低了热导率。然而，CeFe4Sb12 在 823 K 时表现出 ZT = 0.70 的最大性能。在 PryFe4-xCoxSb12 的情况中，Pr 填充引起的声子散射和 Co 取代引起的额外晶格散射导致热导率降低；因此，Pr0.8Fe3CoSb12 在 723 K 时的 ZT = 0.89。在 NdyFe4-xCoxSb12 的情况下，通过调整 Nd 的填充和 Co 的替代，声子散射增强，导致热导率降低；Nd0.对于 YbyFe4-xCoxSb12，Yb0.9Fe3CoSb12 在 823 K 时的热电性能为 ZT = 0.56。9Fe3.5Co0.5Sb12沸石的热电性能最好，为了验证其热电性能的均匀性和可重复性，我们将其制备成体积较大的压块。
{"title":"Skutterudite: Reproducibility of Thermoelectric Performance of P-type RyFe4-xCoxSb12 Bulky Compacts","authors":"Jin-Sol Kim, D. Shin, K. Park, Il-Ho Kim","doi":"10.3365/kjmm.2024.62.7.542","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.7.542","url":null,"abstract":"Skutterudite compounds have excellent thermoelectric performance in the intermediate-to high temperature range. Their lattice thermal conductivity can be reduced by intensifying phonon scattering through independent vibrations of the guest atoms, by filling the voids within the lattice. Furthermore, the thermoelectric figure of merit (ZT) can be enhanced by optimizing the carrier concentration through charge compensation between transition elements. In this study, we compared the thermoelectric properties of p-type filled skutterudite materials, R<sub>y</sub>Fe<sub>4-x</sub>Co<sub>x</sub>Sb<sub>12</sub>, where R represents rare-earth elements (La/Ce/Pr/Nd/Yb), which were filled in the voids, and Co was charge-compensated at the Fe site. In the case of La<sub>y</sub>Fe<sub>4-x</sub>Co<sub>x</sub>Sb<sub>12</sub>, the introduction of La filling and Co doping led La<sub>0.9</sub>Fe<sub>3</sub>CoSb<sub>12</sub> to exhibit a high power factor and low thermal conductivity (ZT = 0.67 at 723 K). In the case of Ce<sub>y</sub>Fe<sub>4-x</sub>Co<sub>x</sub>Sb<sub>12</sub>, in addition to Ce filling, the substitution of Co for Fe resulted in additional lattice scattering, leading to a decrease in thermal conductivity. However, CeFe<sub>4</sub>Sb<sub>12</sub> exhibited a maximum performance of ZT = 0.70 at 823 K. In the case of Pr<sub>y</sub>Fe<sub>4-x</sub>Co<sub>x</sub>Sb<sub>12</sub>, the thermal conductivity was reduced through phonon scattering induced by Pr filling and additional lattice scattering caused by Co substitution; as a result, Pr<sub>0.8</sub>Fe<sub>3</sub>CoSb<sub>12</sub> exhibited ZT = 0.89 at 723 K. In the case of Nd<sub>y</sub>Fe<sub>4-x</sub>Co<sub>x</sub>Sb<sub>12</sub>, the phonon scattering was enhanced by adjusting the filling of Nd and substitution of Co, resulting in a lower thermal conductivity; Nd<sub>0.9</sub>Fe<sub>3.5</sub>Co<sub>0.5</sub>Sb<sub>12</sub> exhibited ZT = 0.91 at 723 K. For Yb<sub>y</sub>Fe<sub>4-x</sub>Co<sub>x</sub>Sb<sub>12</sub>, Yb<sub>0.9</sub>Fe<sub>3</sub>CoSb<sub>12</sub> exhibited a thermoelectric performance of ZT = 0.56 at 823 K. In addition, in this study, for the fabrication (application) of thermoelectric modules, the p-type Nd<sub>0.9</sub>Fe<sub>3.5</sub>Co<sub>0.5</sub>Sb<sub>12</sub> skutterudite, which exhibited the best thermoelectric performance, was prepared in bulky compacts to verify the uniformity and reproducibility of its thermoelectric performance.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141674617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.3365/kjmm.2024.62.6.455
Byoungnam Park
This research explores how aggregation influences the electrical behavior at both the planar - heterojunction poly(3-hexylthiophene) (P3HT)/SiO2 and P3HT/ZnO nanocrystal (NC) interfaces. The formation of H- and J-type aggregates leads to distinct molecular ordering and packing structures, manifesting as changes in threshold voltage shifts (electrical gating) as well as absorption and luminescence properties. Ultrasound irradiation (sonication) significantly alters the molecular arrangement in P3HT, favoring the formation of H-aggregates over the typically formed J-aggregates. In pristine P3HT, J-aggregates facilitate efficient exciton movement and electrical generation, resulting in higher photocurrents compared to sonicated-P3HT, which predominantly forms H-aggregates. Field-effect transistors (FETs) based on sonicated P3HT exhibit a more positive threshold voltage and increased mobility, indicating the presence of more mobile charge carriers, even in the absence of an applied voltage. In interfaces with ZnO NC, pristine P3HT demonstrates a considerable shift in threshold voltage under illumination, attributed to electron trapping. Conversely, sonicated P3HT interfaced with ZnO NC shows less electron trapping and minimal change in threshold voltage. This study underscores how the type of aggregate (H or J) in P3HT significantly dictates light-induced electrical gating. Ultrasound irradiation (sonication), while enhancing mobility by improving crystallinity, leads to a decrease in photocurrent efficiency in H-aggregates compared to the J-aggregates present in pristine-P3HT.
{"title":"Polymer-Chain Aggregation-induced Electrical Gating at the H- and J-aggregate P3HT","authors":"Byoungnam Park","doi":"10.3365/kjmm.2024.62.6.455","DOIUrl":"https://doi.org/10.3365/kjmm.2024.62.6.455","url":null,"abstract":"This research explores how aggregation influences the electrical behavior at both the planar - heterojunction poly(3-hexylthiophene) (P3HT)/SiO2 and P3HT/ZnO nanocrystal (NC) interfaces. The formation of H- and J-type aggregates leads to distinct molecular ordering and packing structures, manifesting as changes in threshold voltage shifts (electrical gating) as well as absorption and luminescence properties. Ultrasound irradiation (sonication) significantly alters the molecular arrangement in P3HT, favoring the formation of H-aggregates over the typically formed J-aggregates. In pristine P3HT, J-aggregates facilitate efficient exciton movement and electrical generation, resulting in higher photocurrents compared to sonicated-P3HT, which predominantly forms H-aggregates. Field-effect transistors (FETs) based on sonicated P3HT exhibit a more positive threshold voltage and increased mobility, indicating the presence of more mobile charge carriers, even in the absence of an applied voltage. In interfaces with ZnO NC, pristine P3HT demonstrates a considerable shift in threshold voltage under illumination, attributed to electron trapping. Conversely, sonicated P3HT interfaced with ZnO NC shows less electron trapping and minimal change in threshold voltage. This study underscores how the type of aggregate (H or J) in P3HT significantly dictates light-induced electrical gating. Ultrasound irradiation (sonication), while enhancing mobility by improving crystallinity, leads to a decrease in photocurrent efficiency in H-aggregates compared to the J-aggregates present in pristine-P3HT.","PeriodicalId":17894,"journal":{"name":"Korean Journal of Metals and Materials","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141265332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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