The objective of this study was to optimize the cooling conditions after solution treatment of the JIS AC4CH aluminum casting alloy, and the effects of the temperature range cooled at 0.5°C/s on the microstructure and mechanical properties were investigated. The temperature range of the cooling and cooling rate were simultaneously adjusted by heating using a high-frequency induction heating apparatus and cooling by blowing air. In particular, cooling at 10°C/s (CR10) was used as the basic cooling rate, with a rate of 0.5°C/s (CR0.5) used for a portion of the temperature range. The scanning electron microscopy (SEM) observations of the specimens after cooling revealed that rod-like precipitates formed in the specimens that were cooled at CR0.5 in the range of 400–250°C. In the specimen that was cooled at CR0.5 from 500 to 450°C, granular or rod-shaped precipitates with a small aspect ratio were observed. From the results of a scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM-EDS) investigation, the former were identified as the Mg2Si intermediate phase, and the latter were composed mainly of Si. An electron probe micro analyzer (EPMA) was used to measure the Mg and Si concentrations in the primary α-Al phase. In the case of the temperature range for CR0.5 cooling above 350°C, the Si concentration decreased significantly as the temperature range of CR0.5 cooling increased. Considering the Si concentration distribution and diffusion distance in the primary α-Al phase, this decrease in the Si concentration could have been caused by the diffusion of Si atoms to the eutectic region. The 0.2% proof stress and tensile strength values after the artificial aging of a specimen that was cooled at CR0.5 from 400 to 350°C, where a coarse Mg2Si intermediate phase precipitated during cooling, were approximately 10% lower than those of a specimen that was cooled at CR10 over the whole temperature range.
{"title":"Effects of Cooling Conditions Immediately after Solution Treatment on Microstructures and Mechanical Properties of JIS AC4CH Aluminum Casting Alloy","authors":"Naohiro Saruwatari, Sumiya Koike, Eiji Sekiya, Yoshihiro Nakayama","doi":"10.2320/matertrans.mt-f2023001","DOIUrl":"https://doi.org/10.2320/matertrans.mt-f2023001","url":null,"abstract":"The objective of this study was to optimize the cooling conditions after solution treatment of the JIS AC4CH aluminum casting alloy, and the effects of the temperature range cooled at 0.5°C/s on the microstructure and mechanical properties were investigated. The temperature range of the cooling and cooling rate were simultaneously adjusted by heating using a high-frequency induction heating apparatus and cooling by blowing air. In particular, cooling at 10°C/s (CR10) was used as the basic cooling rate, with a rate of 0.5°C/s (CR0.5) used for a portion of the temperature range. The scanning electron microscopy (SEM) observations of the specimens after cooling revealed that rod-like precipitates formed in the specimens that were cooled at CR0.5 in the range of 400–250°C. In the specimen that was cooled at CR0.5 from 500 to 450°C, granular or rod-shaped precipitates with a small aspect ratio were observed. From the results of a scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM-EDS) investigation, the former were identified as the Mg2Si intermediate phase, and the latter were composed mainly of Si. An electron probe micro analyzer (EPMA) was used to measure the Mg and Si concentrations in the primary α-Al phase. In the case of the temperature range for CR0.5 cooling above 350°C, the Si concentration decreased significantly as the temperature range of CR0.5 cooling increased. Considering the Si concentration distribution and diffusion distance in the primary α-Al phase, this decrease in the Si concentration could have been caused by the diffusion of Si atoms to the eutectic region. The 0.2% proof stress and tensile strength values after the artificial aging of a specimen that was cooled at CR0.5 from 400 to 350°C, where a coarse Mg2Si intermediate phase precipitated during cooling, were approximately 10% lower than those of a specimen that was cooled at CR10 over the whole temperature range.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"349 1-3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112245","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 : 2023-11-01DOI: 10.2320/matertrans.mt-mi2022006
Parviz Kahhal, Hossein Ghorbani-Menghari, Hwi-Jun Kim, Hyunjoo Choi, Pil-Ryung Cha, Ji Hoon Kim
A neural network-based approach is proposed to minimize the maximum axial stress in the powder forming process. The finite element analysis was conducted using a MATLAB code and an ABAQUS python script to generate observations for the neural network training procedure. Powders of three different particle size distributions were mixed, and the mixture fractions were considered as control parameters. The artificial neural network determined the relationship between parameters and objective function. The effect of mixture fractions on maximum axial stress was analyzed. The results showed that the genetic algorithm could effectively determine the optima and the proposed method had strong prediction capability and accuracy.
{"title":"Metaheuristic Optimization of Powder Size Distribution in Powder Forming Process Using Multi-Particle Finite Element Method Coupled with Artificial Neural Network and Genetic Algorithm","authors":"Parviz Kahhal, Hossein Ghorbani-Menghari, Hwi-Jun Kim, Hyunjoo Choi, Pil-Ryung Cha, Ji Hoon Kim","doi":"10.2320/matertrans.mt-mi2022006","DOIUrl":"https://doi.org/10.2320/matertrans.mt-mi2022006","url":null,"abstract":"A neural network-based approach is proposed to minimize the maximum axial stress in the powder forming process. The finite element analysis was conducted using a MATLAB code and an ABAQUS python script to generate observations for the neural network training procedure. Powders of three different particle size distributions were mixed, and the mixture fractions were considered as control parameters. The artificial neural network determined the relationship between parameters and objective function. The effect of mixture fractions on maximum axial stress was analyzed. The results showed that the genetic algorithm could effectively determine the optima and the proposed method had strong prediction capability and accuracy.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"348 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112247","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 : 2023-11-01DOI: 10.2320/matertrans.mt-m2023077
Nguyen Hai Yen, Kieu Xuan Hau, Nguyen Huy Ngoc, Pham Thi Thanh, Truong Viet Anh, Nguyen Huy Dan
In this work, we investigated the influence of Co on the structure and magnetic properties of Ni50−xCoxMn29Ga21 (x = 0, 2, 4, 6, and 8) shape memory alloy ribbons fabricated by using the melt-spinning method. The addition of Co increases the formation of the austenitic crystalline phase in the alloy ribbons. The crystalline grains in rod-shapes with diameter of ∼2 µm and length of ∼10 µm are mostly oriented perpendicular to the ribbon surface. The martensitic-austenitic transformation was performed on both the thermomagnetization and differential scanning calorimetry methods. With the increase of Co concentration, the martensitic-austenitic structural phase transformation temperature (TM-A) of the alloy gradually decreases while the Curie temperature of the austenite phase (TCA) of the alloy increases from 355 K (for x = 0) to 432 K (for x = 8). Besides, the martensitic-austenitic phase transformation is also significantly affected by the external magnetic field. The structural phase transformation temperature of the alloy tends to shift towards lower temperatures as the external magnetic field increases.
本文研究了Co对熔体纺丝法制备Ni50−xCoxMn29Ga21 (x = 0,2,4,6和8)形状记忆合金带的结构和磁性能的影响。Co的加入增加了合金带中奥氏体晶相的形成。直径为~ 2µm、长度为~ 10µm的棒状晶粒大多垂直于带状表面。用热磁化法和差示扫描量热法分别进行了马氏体-奥氏体相变。随着Co浓度的增加，合金的马氏体-奥氏体组织相变温度(TM-A)逐渐降低，而合金的奥氏体相居里温度(TCA)从355 K (x = 0时)升高到432 K (x = 8时)，马氏体-奥氏体相变也受外加磁场的显著影响。随着外加磁场的增大，合金的组织相变温度有向低温方向移动的趋势。
{"title":"Influence of Co on Structure and Magnetic Properties of Ni<sub>50−x</sub>Co<sub>x</sub>Mn<sub>29</sub>Ga<sub>21</sub> Shape Memory Alloy Ribbons","authors":"Nguyen Hai Yen, Kieu Xuan Hau, Nguyen Huy Ngoc, Pham Thi Thanh, Truong Viet Anh, Nguyen Huy Dan","doi":"10.2320/matertrans.mt-m2023077","DOIUrl":"https://doi.org/10.2320/matertrans.mt-m2023077","url":null,"abstract":"In this work, we investigated the influence of Co on the structure and magnetic properties of Ni50−xCoxMn29Ga21 (x = 0, 2, 4, 6, and 8) shape memory alloy ribbons fabricated by using the melt-spinning method. The addition of Co increases the formation of the austenitic crystalline phase in the alloy ribbons. The crystalline grains in rod-shapes with diameter of ∼2 µm and length of ∼10 µm are mostly oriented perpendicular to the ribbon surface. The martensitic-austenitic transformation was performed on both the thermomagnetization and differential scanning calorimetry methods. With the increase of Co concentration, the martensitic-austenitic structural phase transformation temperature (TM-A) of the alloy gradually decreases while the Curie temperature of the austenite phase (TCA) of the alloy increases from 355 K (for x = 0) to 432 K (for x = 8). Besides, the martensitic-austenitic phase transformation is also significantly affected by the external magnetic field. The structural phase transformation temperature of the alloy tends to shift towards lower temperatures as the external magnetic field increases.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"348 8-9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112248","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 : 2023-11-01DOI: 10.2320/matertrans.mt-m2023091
Hideo Nakajima
Open-channel aluminum with directional holes is fabricated by extraction of stainless steel wires coated with release agent, boron nitride, which are embedded in solidified aluminum. In order to extract the wires from aluminum, tensile force is necessary. If a number of wires can be extracted simultaneously, the production of open-channel aluminum with many holes becomes feasible. Smaller extraction force is desirable to fabricate open-channel aluminum with holes as many as possible. It was found that the extraction force decreases remarkably by adding magnesium hydride to boron nitride because of forming porous layers between the wires and aluminum during melting of aluminum. Besides, the extraction force is also investigated as functions of diameter and length of stainless steel wires, which decreases with decreasing diameter and length of the template wires. The results show that small contact area of the wire to aluminum results in smaller extraction force, which is attributed to decrease in friction force of the wires to aluminum.
{"title":"Fabrication of Open-Channel Aluminum by Template-Extraction Technique","authors":"Hideo Nakajima","doi":"10.2320/matertrans.mt-m2023091","DOIUrl":"https://doi.org/10.2320/matertrans.mt-m2023091","url":null,"abstract":"Open-channel aluminum with directional holes is fabricated by extraction of stainless steel wires coated with release agent, boron nitride, which are embedded in solidified aluminum. In order to extract the wires from aluminum, tensile force is necessary. If a number of wires can be extracted simultaneously, the production of open-channel aluminum with many holes becomes feasible. Smaller extraction force is desirable to fabricate open-channel aluminum with holes as many as possible. It was found that the extraction force decreases remarkably by adding magnesium hydride to boron nitride because of forming porous layers between the wires and aluminum during melting of aluminum. Besides, the extraction force is also investigated as functions of diameter and length of stainless steel wires, which decreases with decreasing diameter and length of the template wires. The results show that small contact area of the wire to aluminum results in smaller extraction force, which is attributed to decrease in friction force of the wires to aluminum.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"348 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112063","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}
Extruded profiles of Al–Mg–Si alloys are typically used in automotive applications. In this study, the microstructure of 6000-series alloys was improved in terms of the energy absorption property (bendability) using the shear stress and flow velocity generated during extrusion instead of conventional transition-metal alloying, because the latter presents challenges in reuse and recycling. This was accomplished using dies with different numbers of feeder holes. Furthermore, in a novel step, complementary finite element analysis (FEA) was conducted to investigate the effects of this improvement on microstructure strengthening. FEA results indicated that the profile obtained using the 4-hole die had lower internal shear stress distribution and aluminum flow velocity than using the 5-hole die. Cross-sectional electron backscatter diffraction observations revealed that the microstructure of the profile obtained using the 4-hole die had fine crystal grains and a strong internal cube or Goss preferential orientation, whereas that obtained using the 5-hole die exhibited coarse grains and an increased number of intermediate orientations. Consequently, the profile obtained using the 4-hole die exhibited improved bendability; furthermore, this die maintained the same tensile strength as the other specimen. Reducing the processing shear stress and flow velocity during extrusion allowed grain refinement and improved bendability at the same tensile strength.
{"title":"Improving Bendability of 6000-Series Extruded Aluminum Profiles Using Dies through Shear Stress and Flow-Velocity Reduction","authors":"Shogo Oda, Takeshi Hashiba, Daichi Terada, Yasuaki Tanaka, Katsuhiko Shiotsuki","doi":"10.2320/matertrans.mt-l2023007","DOIUrl":"https://doi.org/10.2320/matertrans.mt-l2023007","url":null,"abstract":"Extruded profiles of Al–Mg–Si alloys are typically used in automotive applications. In this study, the microstructure of 6000-series alloys was improved in terms of the energy absorption property (bendability) using the shear stress and flow velocity generated during extrusion instead of conventional transition-metal alloying, because the latter presents challenges in reuse and recycling. This was accomplished using dies with different numbers of feeder holes. Furthermore, in a novel step, complementary finite element analysis (FEA) was conducted to investigate the effects of this improvement on microstructure strengthening. FEA results indicated that the profile obtained using the 4-hole die had lower internal shear stress distribution and aluminum flow velocity than using the 5-hole die. Cross-sectional electron backscatter diffraction observations revealed that the microstructure of the profile obtained using the 4-hole die had fine crystal grains and a strong internal cube or Goss preferential orientation, whereas that obtained using the 5-hole die exhibited coarse grains and an increased number of intermediate orientations. Consequently, the profile obtained using the 4-hole die exhibited improved bendability; furthermore, this die maintained the same tensile strength as the other specimen. Reducing the processing shear stress and flow velocity during extrusion allowed grain refinement and improved bendability at the same tensile strength.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"348 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112251","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}
Solid electrolytes with high Li+ conductivity and excellent electrochemical stability are required for the realization of all-solid-state lithium-ion batteries. In this study, LiCsF2, which has been proposed to possess a wide electrochemical stability window, was fabricated and its ion-conduction properties were investigated. LiCsF2 and Mg2+–LiCsF2 were fabricated via ball milling. The dissolution of MgF2 in LiCsF2 via variation of the lattice parameters of LiCsF2 was suggested. The conductivity of LiCsF2 was of the order of 10−8 S/cm at room temperature, and the activation energy for ion conduction was estimated as 1.3 eV. Li deposition/dissolution currents were not clearly observed in the cyclic voltammetry (CV) curves of Mg2+–LiCsF2. The conductivity of Mg2+–LiCsF2 significantly increased upon increasing the relative humidity of the measurement atmosphere. Based on the voltage variation in the water vapor concentration cell, it was concluded that the major conduction carrier in Mg2+–LiCsF2 after exposure to moisture was H+.
{"title":"Ion-Conduction Properties of LiCsF<sub>2</sub>-Based Fluoride Materials","authors":"Reona Miyazaki, Genki Yamaguchi, En Yagi, Yoshimasa Kobayashi, Toshihiro Yoshida, Yuji Katsuda","doi":"10.2320/matertrans.mt-m2023101","DOIUrl":"https://doi.org/10.2320/matertrans.mt-m2023101","url":null,"abstract":"Solid electrolytes with high Li+ conductivity and excellent electrochemical stability are required for the realization of all-solid-state lithium-ion batteries. In this study, LiCsF2, which has been proposed to possess a wide electrochemical stability window, was fabricated and its ion-conduction properties were investigated. LiCsF2 and Mg2+–LiCsF2 were fabricated via ball milling. The dissolution of MgF2 in LiCsF2 via variation of the lattice parameters of LiCsF2 was suggested. The conductivity of LiCsF2 was of the order of 10−8 S/cm at room temperature, and the activation energy for ion conduction was estimated as 1.3 eV. Li deposition/dissolution currents were not clearly observed in the cyclic voltammetry (CV) curves of Mg2+–LiCsF2. The conductivity of Mg2+–LiCsF2 significantly increased upon increasing the relative humidity of the measurement atmosphere. Based on the voltage variation in the water vapor concentration cell, it was concluded that the major conduction carrier in Mg2+–LiCsF2 after exposure to moisture was H+.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"348 5-6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112250","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}
In former studied, authors have already succeeded to get chill-free spheroidal graphite iron castings of φ35 × t5.4 mm indicator sample and automobile knuckle, using permanent mold in as-cast condition. The process of melting, molten treatment and pouring were theoretically designed considering both the reduction and increase of free nitrogen (NF), but it was not analytically proved by actual data yet. In this study, the amount of NF was analyzed using chill samples, which were taken at critical points like melting and molten treatment. As the results, the processes which reduce and increase NF were made clear. The increasing NF was occurred on the process during heating up, carbon addition and temperature slightly increased at near the TEC. The decreasing NF was occurred the process of alloy addition, during super-heating and temperature decreased at under the TEC. Furthermore, as the amount of molten metal decarburization increased, the variation of NF changed from adsorption to denitrification.
{"title":"Quantitative Change of Nitrogen States in Melting Process for Permanent Mold Casting of Spheroidal Graphite Iron","authors":"Kazuya Edane, Haruki Itofuji, Kazuhiro Matsugi, Yong Bum Choi, Hitoshi Kambayashi","doi":"10.2320/matertrans.f-m2023808","DOIUrl":"https://doi.org/10.2320/matertrans.f-m2023808","url":null,"abstract":"In former studied, authors have already succeeded to get chill-free spheroidal graphite iron castings of φ35 × t5.4 mm indicator sample and automobile knuckle, using permanent mold in as-cast condition. The process of melting, molten treatment and pouring were theoretically designed considering both the reduction and increase of free nitrogen (NF), but it was not analytically proved by actual data yet. In this study, the amount of NF was analyzed using chill samples, which were taken at critical points like melting and molten treatment. As the results, the processes which reduce and increase NF were made clear. The increasing NF was occurred on the process during heating up, carbon addition and temperature slightly increased at near the TEC. The decreasing NF was occurred the process of alloy addition, during super-heating and temperature decreased at under the TEC. Furthermore, as the amount of molten metal decarburization increased, the variation of NF changed from adsorption to denitrification.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"349 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112244","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 : 2023-11-01DOI: 10.2320/matertrans.mt-m2023089
Ryota Kondo, Yoshihiro Myokai, Yasushi Obora, Hiroyuki T. Takeshita
This study achieves an increase in Pd concentration on the surface of Ti–Pd alloys using hydrogen peroxide as a green dealloying method, as well as determining the effect of Pd on the hydrogenation of the Ti–Pd alloys. Spontaneous oxidation of Ti in Ti–Pd alloys has been reported to precipitate low-valent Pd on the surface, which can be used for fast δ-TiH2 formation and as a catalyst for various organic reactions. On the other hand, spontaneous oxidation has limited potential to increase the surface Pd concentration. As most of the Pd remains in the metallic phase, there is a need to increase the utilization of the remaining Pd. H2O2 is known to be a green oxidant and also forms complexes with Ti, therefore surface Pd enrichment by dealloying is expected. This study was carried out to investigate the relationship between hydrogenation and surface properties of Ti–Pd alloys by H2O2 immersion. The increase in the thickness of Ti oxide layers and the increase in Pd concentration on Ti–Pd alloys were found by H2O2 immersion. Model experiments on chip-like specimens showed that the Ti oxide layer retards hydrogen diffusion, while the Pd on the surface has the effect of increasing the hydrogen supply to the metallic phase. Pd on the surface was also found to have an effect on the fast decomposition of H2O2. These results indicate that H2O2 immersion is effective as a surface treatment to increase the Pd concentration on the surface with reduced Ti dissolution.
{"title":"Surface Structures and Hydrogenation Properties of Ti–Pd Alloys Immersed in Hydrogen Peroxide","authors":"Ryota Kondo, Yoshihiro Myokai, Yasushi Obora, Hiroyuki T. Takeshita","doi":"10.2320/matertrans.mt-m2023089","DOIUrl":"https://doi.org/10.2320/matertrans.mt-m2023089","url":null,"abstract":"This study achieves an increase in Pd concentration on the surface of Ti–Pd alloys using hydrogen peroxide as a green dealloying method, as well as determining the effect of Pd on the hydrogenation of the Ti–Pd alloys. Spontaneous oxidation of Ti in Ti–Pd alloys has been reported to precipitate low-valent Pd on the surface, which can be used for fast δ-TiH2 formation and as a catalyst for various organic reactions. On the other hand, spontaneous oxidation has limited potential to increase the surface Pd concentration. As most of the Pd remains in the metallic phase, there is a need to increase the utilization of the remaining Pd. H2O2 is known to be a green oxidant and also forms complexes with Ti, therefore surface Pd enrichment by dealloying is expected. This study was carried out to investigate the relationship between hydrogenation and surface properties of Ti–Pd alloys by H2O2 immersion. The increase in the thickness of Ti oxide layers and the increase in Pd concentration on Ti–Pd alloys were found by H2O2 immersion. Model experiments on chip-like specimens showed that the Ti oxide layer retards hydrogen diffusion, while the Pd on the surface has the effect of increasing the hydrogen supply to the metallic phase. Pd on the surface was also found to have an effect on the fast decomposition of H2O2. These results indicate that H2O2 immersion is effective as a surface treatment to increase the Pd concentration on the surface with reduced Ti dissolution.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"348 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112246","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 : 2023-11-01DOI: 10.2320/matertrans.mt-m2023105
Lidan Qu, Jiaqiang Ni, Xiaodan Li, Yi Lu, Bingzhi Chen
One challenge hampering the structural applications of High-entropy alloys (HEAs) is to overcome the strength-ductility trade-off. Inspired by nature, engineering the HEAs with laminated structure composed of alternating soft and hard layers has the potential to strengthen the HEAs while maintaining the ductility. Here, taking the AlxCrMnFeCoNi HEA as the model material, the laminated HEAs composed by soft and hard layers were successfully prepared by laser additive manufacturing (LAM). The soft and hard laminated layers were achieved through tailoring the Al content. In several combinations of hard and soft, the strength of Al10–Al12 was significantly higher than that of Al12 HEA, indicating that an appropriate soft and hard matching can indeed further strengthen the HEA compared with the homogeneous HEA.
{"title":"Laser Additive Manufacturing of Laminated AlCrMnFeCoNi High Entropy Alloys","authors":"Lidan Qu, Jiaqiang Ni, Xiaodan Li, Yi Lu, Bingzhi Chen","doi":"10.2320/matertrans.mt-m2023105","DOIUrl":"https://doi.org/10.2320/matertrans.mt-m2023105","url":null,"abstract":"One challenge hampering the structural applications of High-entropy alloys (HEAs) is to overcome the strength-ductility trade-off. Inspired by nature, engineering the HEAs with laminated structure composed of alternating soft and hard layers has the potential to strengthen the HEAs while maintaining the ductility. Here, taking the AlxCrMnFeCoNi HEA as the model material, the laminated HEAs composed by soft and hard layers were successfully prepared by laser additive manufacturing (LAM). The soft and hard laminated layers were achieved through tailoring the Al content. In several combinations of hard and soft, the strength of Al10–Al12 was significantly higher than that of Al12 HEA, indicating that an appropriate soft and hard matching can indeed further strengthen the HEA compared with the homogeneous HEA.","PeriodicalId":18402,"journal":{"name":"Materials Transactions","volume":"348 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135112249","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 : 2023-10-01DOI: 10.2320/matertrans.mt-m2023080
Hiroaki Yamamoto, Masamori Akiguchi, Hiroki Kominato, Ai Nozaki, Masao Morishita
The electrodeposition of bismuth–tellurium thermoelectric material was investigated by galvanostatic and potentiostatic electrolysis in ethylene glycol (EG)-BiCl3–TeCl4 non-aqueous solutions at 393 K. Controlling the molar ratio of BiCl3 to TeCl4 in the bath and the electrolysis conditions, the Bi–Te alloys with various compositions were electrodeposited. The composition of the electrodeposit obtained in the 97.50 mol%EG-2.45 mol%BiCl3–0.05 mol%TeCl4 bath with the BiCl3 to TeCl4 molar ratio of 50:1 at the current density of 20 A·m−2 was 40.14 mol%Bi–59.86 mol%Te and close to that of Bi2Te3. This electrodeposit exhibited a n-type thermoelectric conversion for the given temperature difference and its Seebeck coefficient was −145 µV K−1.
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