Pub Date : 2024-10-30DOI: 10.1016/j.intermet.2024.108532
Jian Wang , Bin Liu , Hui Zhou , Yuankui Cao , Qianli Huang , Bingfeng Wang , Jia Li , Qihong Fang , Ao Fu , Yong Liu
In this work, an oxide-dispersion strengthened (ODS) FeCrNi medium entropy alloy (MEA) was prepared by low-energy ball milling and laser powder bed fusion (PBF-LB/M). The ODS FeCrNi MEA shows remarkable room-temperature tensile properties with yield strength of 878 MPa, ultimate tensile strength of 1070 MPa, and elongation of 30 %. Meanwhile, its high-temperature strength at 400 °C, 600 °C, and 700 °C exceeds many typical ODS alloys, such as PM 2000 and ODS 316. The ultra-fine cellular structures and uniformly dispersed nano-Y2O3 particles in the PBF-LB/M ODS FeCrNi MEA are the main reasons for its high strength. Additionally, the FCC-matrix with a high deformation capacity and the semi-coherent interface relationship between the FCC-matrix and the nano-Y2O3 particles ensure adequate plasticity.
{"title":"Additive manufactured oxide-dispersion strengthened FeCrNi medium entropy alloy with superior mechanical properties","authors":"Jian Wang , Bin Liu , Hui Zhou , Yuankui Cao , Qianli Huang , Bingfeng Wang , Jia Li , Qihong Fang , Ao Fu , Yong Liu","doi":"10.1016/j.intermet.2024.108532","DOIUrl":"10.1016/j.intermet.2024.108532","url":null,"abstract":"<div><div>In this work, an oxide-dispersion strengthened (ODS) FeCrNi medium entropy alloy (MEA) was prepared by low-energy ball milling and laser powder bed fusion (PBF-LB/M). The ODS FeCrNi MEA shows remarkable room-temperature tensile properties with yield strength of 878 MPa, ultimate tensile strength of 1070 MPa, and elongation of 30 %. Meanwhile, its high-temperature strength at 400 °C, 600 °C, and 700 °C exceeds many typical ODS alloys, such as PM 2000 and ODS 316. The ultra-fine cellular structures and uniformly dispersed nano-Y<sub>2</sub>O<sub>3</sub> particles in the PBF-LB/M ODS FeCrNi MEA are the main reasons for its high strength. Additionally, the FCC-matrix with a high deformation capacity and the semi-coherent interface relationship between the FCC-matrix and the nano-Y<sub>2</sub>O<sub>3</sub> particles ensure adequate plasticity.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108532"},"PeriodicalIF":4.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nb-rich γ-TiAl alloys are of interest for enhanced mechanical properties and oxidation resistance. The influence of cooling rate and annealing duration on microstructural evolution of Nb-rich γ-TiAl alloy (Ti-45Al-8Nb-0.2B) has been meticulously investigated, with emphasis on phase volume fraction, grain size, and lamellar spacing. The alloy was annealed at 1320 °C for 15 min, and then furnace-cooled, oil-quenched or cryogenic quenched, whereas annealing for 2 h and 26 h was followed by water quenching. The post-anneal microstructures were characterized using X-ray diffraction, optical and scanning electron microscopy, along with energy dispersive spectroscopy and electron backscattered diffraction. Across all samples, a fully lamellar microstructure comprising α2 and γ phases has been consistently achieved, along with sporadically observed small β precipitates, and elongated ribbon-like TiB2. Widmannstätten colonies (WC) have been observed with diverse morphologies, most of which exhibited an angle of around 64° to regular lamellae, supporting the theory of twinning in the α-phase for WC formation. The γ phase fraction has decreased with increasing cooling rate and annealing time. Grain size and lamellar spacing have also declined with cooling rate but increased with annealing time. Additionally, the mean size of equiaxed γ grains has enlarged with annealing duration.
{"title":"Statistical analysis of lamellar and Widmannstätten structures obtained in Nb-rich γ-TiAl alloy with varied cooling rate and annealing duration","authors":"Raashid Firoz , R.S.K. Gudavalli , Amlan Dutta , Chandan Mondal , Rahul Mitra","doi":"10.1016/j.intermet.2024.108529","DOIUrl":"10.1016/j.intermet.2024.108529","url":null,"abstract":"<div><div>Nb-rich γ-TiAl alloys are of interest for enhanced mechanical properties and oxidation resistance. The influence of cooling rate and annealing duration on microstructural evolution of Nb-rich γ-TiAl alloy (Ti-45Al-8Nb-0.2B) has been meticulously investigated, with emphasis on phase volume fraction, grain size, and lamellar spacing. The alloy was annealed at 1320 °C for 15 min, and then furnace-cooled, oil-quenched or cryogenic quenched, whereas annealing for 2 h and 26 h was followed by water quenching. The post-anneal microstructures were characterized using X-ray diffraction, optical and scanning electron microscopy, along with energy dispersive spectroscopy and electron backscattered diffraction. Across all samples, a fully lamellar microstructure comprising α<sub>2</sub> and γ phases has been consistently achieved, along with sporadically observed small β precipitates, and elongated ribbon-like TiB<sub>2</sub>. Widmannstätten colonies (WC) have been observed with diverse morphologies, most of which exhibited an angle of around 64° to regular lamellae, supporting the theory of <span><math><mrow><mo>{</mo><mrow><mover><mn>1</mn><mo>‾</mo></mover><mover><mn>1</mn><mo>‾</mo></mover><mn>22</mn></mrow><mo>}</mo></mrow></math></span> twinning in the α-phase for <span>WC</span> formation. The γ phase fraction has decreased with increasing cooling rate and annealing time. Grain size and lamellar spacing have also declined with cooling rate but increased with annealing time. Additionally, the mean size of equiaxed γ grains has enlarged with annealing duration.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108529"},"PeriodicalIF":4.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-28DOI: 10.1016/j.intermet.2024.108536
Haoyu Zhao , Sheng Mou , Shengjie Ren , Jun Liu , Zhexu Li , Kun Bu , Binqiang Wang
Ni-based superalloy turbine blades have been required components in contemporary aero-engine. Knowing the solidification behavior, residual stress at grain defects, and microstructure of directionally solidified turbine blades is a required condition to improve the service performance of directionally solidified turbine blades. Firstly, the temperature field evolution of the blade under the withdrawal rate of 3 mm/min was studied. The deviations in temperature distribution in the high-rate solidification (HRS) procedure, particularly near the platform, can lead to transformations in the mushy zone, potentially resulting in solidification defects. Secondly, the grain growth of hollow turbine blades was calculated using the cellular automaton-finite factor method. The simulated grain framework was essentially consistent with experimental results. A method of process bar addition based on physical field distribution is also proposed. This method involves designing a combination of one Y-shaped and two I-shaped rods to decrease the cooling rate of blade edges and eliminate stray grains (SG). Then, the residual stress distribution at the locations of stray grains and low-angle grain boundaries (LAGBs) was analyzed before and after the addition of process bars. Finally, discussions were held regarding the distribution of γ′ phases in grain defects and blades.
镍基超合金涡轮叶片是当代航空发动机的必备部件。了解定向凝固涡轮叶片的凝固行为、晶粒缺陷处的残余应力和微观结构是提高定向凝固涡轮叶片服役性能的必要条件。首先，研究了叶片在 3 毫米/分钟抽速下的温度场演变。在高速凝固（HRS）过程中，温度分布的偏差，尤其是在平台附近，会导致粘稠区的转变，从而可能导致凝固缺陷。其次，使用单元自动机-有限元法计算了空心涡轮叶片的晶粒生长。模拟晶粒框架与实验结果基本一致。此外，还提出了一种基于物理场分布的工艺棒添加方法。该方法包括设计一个 Y 形棒和两个 I 形棒的组合，以降低叶片边缘的冷却速度并消除杂散晶粒 (SG)。然后，分析了添加加工棒前后杂散晶粒和低角度晶界（LAGB）位置的残余应力分布。最后，讨论了晶粒缺陷和叶片中 γ′ 相的分布。
{"title":"Simulation and experimental investigation of grain structure, residual stress,γ′ phases in single crystal blade","authors":"Haoyu Zhao , Sheng Mou , Shengjie Ren , Jun Liu , Zhexu Li , Kun Bu , Binqiang Wang","doi":"10.1016/j.intermet.2024.108536","DOIUrl":"10.1016/j.intermet.2024.108536","url":null,"abstract":"<div><div>Ni-based superalloy turbine blades have been required components in contemporary aero-engine. Knowing the solidification behavior, residual stress at grain defects, and microstructure of directionally solidified turbine blades is a required condition to improve the service performance of directionally solidified turbine blades. Firstly, the temperature field evolution of the blade under the withdrawal rate of 3 mm/min was studied. The deviations in temperature distribution in the high-rate solidification (HRS) procedure, particularly near the platform, can lead to transformations in the mushy zone, potentially resulting in solidification defects. Secondly, the grain growth of hollow turbine blades was calculated using the cellular automaton-finite factor method. The simulated grain framework was essentially consistent with experimental results. A method of process bar addition based on physical field distribution is also proposed. This method involves designing a combination of one Y-shaped and two I-shaped rods to decrease the cooling rate of blade edges and eliminate stray grains (SG). Then, the residual stress distribution at the locations of stray grains and low-angle grain boundaries (LAGBs) was analyzed before and after the addition of process bars. Finally, discussions were held regarding the distribution of γ′ phases in grain defects and blades.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108536"},"PeriodicalIF":4.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-28DOI: 10.1016/j.intermet.2024.108541
Zhixin Li , Shenghai Wang , Lina Hu
Applying 3D printing technology to high entropy alloys (HEAs) offers new potential for materials design and optimization. However, there is a lack of deep understanding of the microstructure evolution with the element addition to HEAs in 3D printing. How the element addition influences the final microstructure of materials during 3D printing still remains a puzzle. In this study, we investigated the microstructure evolution of CoCrFeNi(AlTi)xwt% (x = 0, 2.5, 5 and 7.5) HEAs fabricated by selective laser melting (SLM). We selected Al and Ti atoms as additions in the CoCrFeNi matrix based on their strong negative mixing enthalpy with Ni elements and larger atom radius than other matrix elements. It has been found that the Al and Ti addition leads to the formation of BCC and B2 precipitates, resulting in different mechanical properties. Yield strength (YS) of the HEAs exhibits a distinct increase from 512.64 MPa to 901.72 MPa at the cost of the ductility. The relationship between mechanical properties and microstructure evolution with Al and Ti additions has been elucidated. It has been found that the formation of a dislocation network in our HEAs serves as nucleation sites to benefit the precipitation. Besides, this network provides a rapid channel for atoms to diffuse during the thermal cycle of 3D printing, which also promotes the formation of precipitates. This research provides valuable insights into the modification of microstructure through SLM, contributing to the development of materials design and optimization in 3D printing.
将三维打印技术应用于高熵合金（HEAs）为材料设计和优化提供了新的潜力。然而，人们对三维打印技术在高熵合金中添加元素后的微观结构演变缺乏深入了解。在三维打印过程中，元素添加如何影响材料的最终微观结构仍是一个难题。在本研究中，我们研究了通过选择性激光熔融（SLM）制造的 CoCrFeNi(AlTi)xwt%（x = 0、2.5、5 和 7.5）HEA 的微观结构演变。我们选择 Al 原子和 Ti 原子作为 CoCrFeNi 基体中的添加物，是因为它们与 Ni 元素的混合焓为负，且原子半径大于其他基体元素。研究发现，Al 和 Ti 的加入会导致 BCC 和 B2 沉淀的形成，从而产生不同的机械性能。HEA 的屈服强度（YS）从 512.64 兆帕明显提高到 901.72 兆帕，但延展性却有所降低。研究还阐明了添加 Al 和 Ti 后机械性能与微观结构演变之间的关系。研究发现，在我们的 HEA 中形成的位错网络是有利于析出的成核点。此外，在三维打印的热循环过程中，这种网络为原子扩散提供了快速通道，这也促进了析出物的形成。这项研究为通过 SLM 改变微观结构提供了宝贵的见解，有助于三维打印中材料设计和优化的发展。
{"title":"Microstructure evolution in 3D-printed CoCrFeNi(AlTi)xwt% (x=0, 2.5, 5 and 7.5) high entropy alloys","authors":"Zhixin Li , Shenghai Wang , Lina Hu","doi":"10.1016/j.intermet.2024.108541","DOIUrl":"10.1016/j.intermet.2024.108541","url":null,"abstract":"<div><div>Applying 3D printing technology to high entropy alloys (HEAs) offers new potential for materials design and optimization. However, there is a lack of deep understanding of the microstructure evolution with the element addition to HEAs in 3D printing. How the element addition influences the final microstructure of materials during 3D printing still remains a puzzle. In this study, we investigated the microstructure evolution of CoCrFeNi(AlTi)<sub>xwt%</sub> (x = 0, 2.5, 5 and 7.5) HEAs fabricated by selective laser melting (SLM). We selected Al and Ti atoms as additions in the CoCrFeNi matrix based on their strong negative mixing enthalpy with Ni elements and larger atom radius than other matrix elements. It has been found that the Al and Ti addition leads to the formation of BCC and B2 precipitates, resulting in different mechanical properties. Yield strength (YS) of the HEAs exhibits a distinct increase from 512.64 MPa to 901.72 MPa at the cost of the ductility. The relationship between mechanical properties and microstructure evolution with Al and Ti additions has been elucidated. It has been found that the formation of a dislocation network in our HEAs serves as nucleation sites to benefit the precipitation. Besides, this network provides a rapid channel for atoms to diffuse during the thermal cycle of 3D printing, which also promotes the formation of precipitates. This research provides valuable insights into the modification of microstructure through SLM, contributing to the development of materials design and optimization in 3D printing.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108541"},"PeriodicalIF":4.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-25DOI: 10.1016/j.intermet.2024.108545
Jiang Li , Xuehan An , Tong Wang , E Zhu , Fuguo Li
In this paper, the thermal deformation behavior of GH4065A alloy at high temperature was studied by thermal simulation compression test. The effects of deformation temperature and strain rate on microstructure evolution and dynamic recrystallization mechanism were studied by electron backscattered diffraction (EBSD) technology and transmission electron microscopy (TEM). It is proved that different deformation parameters lead to significant differences in flow behavior and dynamic recrystallization behavior. The results show that dynamic recrystallization (DRX) fraction and deformation temperature have the same variation trend. In the range of high strain rate, DRX fraction increases with the increase of strain rate. During the hot deformation process, the dynamic recrystallization mechanism of the GH4065A alloy is primarily characterized by discontinuous dynamic recrystallization (DDRX) through the nucleation form of grain boundary bulging. In the γ+γ′ two-phase region, twin-induced recrystallization (TDRX) nucleation and γ′ phase-induced recrystallization (PIDRX) nucleation phenomena are present. As the deformation temperature rises above the dissolution temperature of the γ′ phase, the effects of continuous dynamic recrystallization (CDRX) and TDRX in the deformed samples are diminished. The dissolution of the γ′ phase results in the loss of its pinning effect, while the coarsened γ′ phase significantly reduces its promoting effect on the DRX nucleation process, leading to a notable increase in grain size.
{"title":"Thermal deformation behavior and dynamic recrystallization mechanism of GH4065A alloy considering the effect of γ′ phase","authors":"Jiang Li , Xuehan An , Tong Wang , E Zhu , Fuguo Li","doi":"10.1016/j.intermet.2024.108545","DOIUrl":"10.1016/j.intermet.2024.108545","url":null,"abstract":"<div><div>In this paper, the thermal deformation behavior of GH4065A alloy at high temperature was studied by thermal simulation compression test. The effects of deformation temperature and strain rate on microstructure evolution and dynamic recrystallization mechanism were studied by electron backscattered diffraction (EBSD) technology and transmission electron microscopy (TEM). It is proved that different deformation parameters lead to significant differences in flow behavior and dynamic recrystallization behavior. The results show that dynamic recrystallization (DRX) fraction and deformation temperature have the same variation trend. In the range of high strain rate, DRX fraction increases with the increase of strain rate. During the hot deformation process, the dynamic recrystallization mechanism of the GH4065A alloy is primarily characterized by discontinuous dynamic recrystallization (DDRX) through the nucleation form of grain boundary bulging. In the γ+γ′ two-phase region, twin-induced recrystallization (TDRX) nucleation and γ′ phase-induced recrystallization (PIDRX) nucleation phenomena are present. As the deformation temperature rises above the dissolution temperature of the γ′ phase, the effects of continuous dynamic recrystallization (CDRX) and TDRX in the deformed samples are diminished. The dissolution of the γ′ phase results in the loss of its pinning effect, while the coarsened γ′ phase significantly reduces its promoting effect on the DRX nucleation process, leading to a notable increase in grain size.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108545"},"PeriodicalIF":4.3,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-24DOI: 10.1016/j.intermet.2024.108539
Yulin Jiang , Jianzeng Ren , Xuanxin Jin , Zuyun Yan , Wei Tan , Zhijie Zeng , Anhui Cai , Pengwei Li , Sheng Li
Biomedical Fe-30Mn alloy was a promising alternative for the repair of load-bearing bone defects, but its applications were largely limited by slower degradation rate than growth rate of natural bone. The accelerated corrosion mechanisms of secondary phase MnS in Fe-30Mn-S biocomposite were proposed in the study. Detailly, the MnS with a lower corrosion potential preferentially corroded and thereby increased corrosion active sites. Moreover, adsorbed S element produced by the corrosion of MnS weakened the metal-metal bond of Fe. Meanwhile, Cl− with a small ion radius easily penetrated through degradation products, which made corrosive media inside corrosion pits more aggressive. Thus, the Fe-30Mn-S biocomposite tended to vertically expand during corrosion evolution, and caused rapid corrosion with a considerably increased corrosion rate of 0.41 mm y−1. Besides, the Fe-30Mn-S biocomposite presented an ultimate compressive strength of 687 ± 22 MPa, compressive yield strength of 402 ± 23 MPa, microhardness of 280.4 ± 5.8 HV, and favorable cytocompatibility. These results indicated that Fe-30Mn-S biocomposite with accelerated corrosion effects by secondary phase could be a promising candidate for bone repair.
{"title":"Accelerated biodegradation of Fe-30Mn-S biocomposite via preferential corrosion of secondary phase","authors":"Yulin Jiang , Jianzeng Ren , Xuanxin Jin , Zuyun Yan , Wei Tan , Zhijie Zeng , Anhui Cai , Pengwei Li , Sheng Li","doi":"10.1016/j.intermet.2024.108539","DOIUrl":"10.1016/j.intermet.2024.108539","url":null,"abstract":"<div><div>Biomedical Fe-30Mn alloy was a promising alternative for the repair of load-bearing bone defects, but its applications were largely limited by slower degradation rate than growth rate of natural bone. The accelerated corrosion mechanisms of secondary phase MnS in Fe-30Mn-S biocomposite were proposed in the study. Detailly, the MnS with a lower corrosion potential preferentially corroded and thereby increased corrosion active sites. Moreover, adsorbed S element produced by the corrosion of MnS weakened the metal-metal bond of Fe. Meanwhile, Cl<sup>−</sup> with a small ion radius easily penetrated through degradation products, which made corrosive media inside corrosion pits more aggressive. Thus, the Fe-30Mn-S biocomposite tended to vertically expand during corrosion evolution, and caused rapid corrosion with a considerably increased corrosion rate of 0.41 mm y<sup>−1</sup>. Besides, the Fe-30Mn-S biocomposite presented an ultimate compressive strength of 687 ± 22 MPa, compressive yield strength of 402 ± 23 MPa, microhardness of 280.4 ± 5.8 HV, and favorable cytocompatibility. These results indicated that Fe-30Mn-S biocomposite with accelerated corrosion effects by secondary phase could be a promising candidate for bone repair.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108539"},"PeriodicalIF":4.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An analysis of the first order transition kinetics between D03 and L12 phases in Fe3Ga-type alloy is carried out. Structure and magnetostriction of the samples were carefully controlled by SEM-EBSD analysis and magnetostriction tests after different heat treatments, and additionally in in situ regime by VSM and DSC. C-shaped curves for time-temperature-transition (TTT) diagram based on the results of the EBSD analysis of Fe-27Ga alloy are constructed in the temperature range between 400 and 550 °C. TTT diagram shows that the nucleation rate for L12 phase increases in the sequence 400 → 475 → 550 °C, while the growth rate reaches a maximum at about 500–525 °C. Effect of D03 ↔ L12 thermocycling on the kinetic of the D03 → L12 transition is studied for the first time. The amount of the L12 phase after sample re-quenching and subsequent annealing at the same annealing temperature and time, significantly increases compared with the first cycle quenching and subsequent annealing, demonstrating memory effect of previous transitions.
{"title":"Time temperature transition and effect of thermocycling (D03 ↔ L12) on Fe3Ga-type alloy structure","authors":"V.V. Palacheva , A.A. Shcherbakov , V.V. Cheverikin , E.N. Zanaeva , A.M. Balagurov , I.S. Golovin","doi":"10.1016/j.intermet.2024.108528","DOIUrl":"10.1016/j.intermet.2024.108528","url":null,"abstract":"<div><div>An analysis of the first order transition kinetics between D0<sub>3</sub> and L1<sub>2</sub> phases in Fe<sub>3</sub>Ga-type alloy is carried out. Structure and magnetostriction of the samples were carefully controlled by SEM-EBSD analysis and magnetostriction tests after different heat treatments, and additionally in <em>in situ</em> regime by VSM and DSC. C-shaped curves for time-temperature-transition (TTT) diagram based on the results of the EBSD analysis of Fe-27Ga alloy are constructed in the temperature range between 400 and 550 °C. TTT diagram shows that the nucleation rate for L1<sub>2</sub> phase increases in the sequence 400 → 475 → 550 °C, while the growth rate reaches a maximum at about 500–525 °C. Effect of D0<sub>3</sub> ↔ L1<sub>2</sub> thermocycling on the kinetic of the D0<sub>3</sub> → L1<sub>2</sub> transition is studied for the first time. The amount of the L1<sub>2</sub> phase after sample re-quenching and subsequent annealing at the same annealing temperature and time, significantly increases compared with the first cycle quenching and subsequent annealing, demonstrating memory effect of previous transitions.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108528"},"PeriodicalIF":4.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-24DOI: 10.1016/j.intermet.2024.108546
Hanlin Peng , Siming Huang , Ling Hu , Ian Baker
Large-scale superconducting magnets in ITERs have an increasing need to develop hetero-structured components, which need to join those cryogenic strong, ductile high/medium-entropy alloys (H/MEAs) to traditional austenitic stainless steels (SSs). So far, investigation on the microstructure-strength relationship of HEAs dissimilar welded joints is still lacking, and high-strength ductile joints are being pursued in the welding field. However, the intermixed composition in the fusion zone (FZ) brings great uncertainty in phase stability. In this work, we investigated the dissimilar weldability of MEA Ni43.4Co25.3Cr25.3Al3Ti3 and commercial 316 SS both in 2 mm thickness using electron beam welding (EBW). A full penetration and oxidation-free joint was produced with systematic columnar grains with an average size of 200 μm, which consists of f.c.c. matrix and a few titanium carbides as verified by both thermodynamic calculations and experimental observations. However, some cavities are present due to solidification shrinkage. The weld thermal cycling recrystallizes the MEA to form heat heat-affected zone (HAZ) with grain sizes of 6 μm and commonly observed (110)<112> texture. The 316 SS and its neighboring HAZ have comparable grain sizes of 11∼13 μm and (111)<101> texture. Strong, ductile dissimilar weld joins were developed, e.g. YS of 380 MPa, UTS of 691 MPa, a uniform strain of 17.1 %, and fracture strain of 24.5 % at 298 K, and YS of 480 MPa, UTS of 929 MPa, uniform strain of 17.8 %, and fracture strain of 21.7 % at 77 K. A severe localized strain concentration occurred in the FZ associated with two neighboring HAZs, which makes failure occur in the FZ by a ductile intergranular mode. The plastic deformation is mainly governed by a planar slip of dislocations along with a few stacking faults and deformation twinning events at both temperatures. Pronounced deformation-induced planar defects not only strengthen the strain hardening rate to ductilize but also strengthen the joint.
{"title":"Dissimilar electron beam welding of the medium-entropy alloy Ni43.4Co25.3Cr25.3Al3Ti3 and 316 stainless steel for cryogenic application","authors":"Hanlin Peng , Siming Huang , Ling Hu , Ian Baker","doi":"10.1016/j.intermet.2024.108546","DOIUrl":"10.1016/j.intermet.2024.108546","url":null,"abstract":"<div><div>Large-scale superconducting magnets in ITERs have an increasing need to develop hetero-structured components, which need to join those cryogenic strong, ductile high/medium-entropy alloys (H/MEAs) to traditional austenitic stainless steels (SSs). So far, investigation on the microstructure-strength relationship of HEAs dissimilar welded joints is still lacking, and high-strength ductile joints are being pursued in the welding field. However, the intermixed composition in the fusion zone (FZ) brings great uncertainty in phase stability. In this work, we investigated the dissimilar weldability of MEA Ni<sub>43.4</sub>Co<sub>25.3</sub>Cr<sub>25.3</sub>Al<sub>3</sub>Ti<sub>3</sub> and commercial 316 SS both in 2 mm thickness using electron beam welding (EBW). A full penetration and oxidation-free joint was produced with systematic columnar grains with an average size of 200 μm, which consists of f.c.c. matrix and a few titanium carbides as verified by both thermodynamic calculations and experimental observations. However, some cavities are present due to solidification shrinkage. The weld thermal cycling recrystallizes the MEA to form heat heat-affected zone (HAZ) with grain sizes of 6 μm and commonly observed (110)<112> texture. The 316 SS and its neighboring HAZ have comparable grain sizes of 11∼13 μm and (111)<101> texture. Strong, ductile dissimilar weld joins were developed, e.g. YS of 380 MPa, UTS of 691 MPa, a uniform strain of 17.1 %, and fracture strain of 24.5 % at 298 K, and YS of 480 MPa, UTS of 929 MPa, uniform strain of 17.8 %, and fracture strain of 21.7 % at 77 K. A severe localized strain concentration occurred in the FZ associated with two neighboring HAZs, which makes failure occur in the FZ by a ductile intergranular mode. The plastic deformation is mainly governed by a planar slip of dislocations along with a few stacking faults and deformation twinning events at both temperatures. Pronounced deformation-induced planar defects not only strengthen the strain hardening rate to ductilize but also strengthen the joint.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108546"},"PeriodicalIF":4.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-23DOI: 10.1016/j.intermet.2024.108540
Tiago A. Rodrigues , A. Malfeito , Francisco Werley Cipriano Farias , V. Duarte , João Lopes , João da Cruz Payão Filho , Julian A. Avila , N. Schell , Telmo G. Santos , J.P. Oliveira
In this study, a novel method for enhancing the quality of components fabricated by wire and arc additive manufacturing (WAAM) was developed. This approach employs an innovative mechanism featuring an actuator that dispenses a solution containing refinement particles (TiB2 inoculants), in conjunction with a soldering flux that vaporizes prior to reaching the electric arc. This leaves the particles to adhere to the welding wire or be carried by the shielding gas. By implementing this device, TiB2 particles were successfully incorporated into the molten pool during the WAAM process of Inconel 625 at levels of 0.31 and 0.56 wt%. Microstructural analysis reveals a significant reduction in the size of interdendritic segregation regions when TiB2 particles are introduced. Electron backscatter diffraction analysis further reveals the transformation of columnar grains into equiaxed grains. The average grain area decreased from 1823 μm2 in the as-built sample to 583 μm2 in the sample with a TiB2 content of 0.56 wt%. In addition, an improvement in the Inconel 625 fabricated by WAAM mechanical strength was observed due to the use of TiB2 inoculants, which was primarily attributed to the effect of the grain size refinement.
{"title":"Grain refinement of Inconel 625 during wire-based directed energy deposition additive manufacturing by in-situ added TiB2 particles: Process development, microstructure evolution and mechanical characterization","authors":"Tiago A. Rodrigues , A. Malfeito , Francisco Werley Cipriano Farias , V. Duarte , João Lopes , João da Cruz Payão Filho , Julian A. Avila , N. Schell , Telmo G. Santos , J.P. Oliveira","doi":"10.1016/j.intermet.2024.108540","DOIUrl":"10.1016/j.intermet.2024.108540","url":null,"abstract":"<div><div>In this study, a novel method for enhancing the quality of components fabricated by wire and arc additive manufacturing (WAAM) was developed. This approach employs an innovative mechanism featuring an actuator that dispenses a solution containing refinement particles (TiB<sub>2</sub> inoculants), in conjunction with a soldering flux that vaporizes prior to reaching the electric arc. This leaves the particles to adhere to the welding wire or be carried by the shielding gas. By implementing this device, TiB<sub>2</sub> particles were successfully incorporated into the molten pool during the WAAM process of Inconel 625 at levels of 0.31 and 0.56 wt%. Microstructural analysis reveals a significant reduction in the size of interdendritic segregation regions when TiB<sub>2</sub> particles are introduced. Electron backscatter diffraction analysis further reveals the transformation of columnar grains into equiaxed grains. The average grain area decreased from 1823 μm<sup>2</sup> in the as-built sample to 583 μm<sup>2</sup> in the sample with a TiB<sub>2</sub> content of 0.56 wt%. In addition, an improvement in the Inconel 625 fabricated by WAAM mechanical strength was observed due to the use of TiB<sub>2</sub> inoculants, which was primarily attributed to the effect of the grain size refinement.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108540"},"PeriodicalIF":4.3,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study examines the impact of direct powder forging of powders on the composition, structure, and mechanical properties of iron aluminide Fe–28 at. % Al. During the synthesis and forging of Fe3Al powders, a homogeneous A2 phase is formed at a temperature of 1100 °C. Porosity after forging is 2–2.5 %. Residual pores are predominantly planar in shape and are located at the boundaries of the powder particles. Annealing at 1300 °C improves the quality of interparticle boundaries and all samples exhibit transcrystalline fracture mechanism. Samples forged at 1100 °C and annealed at 1300 °C show maximum strength σbend = 1050 MPa and fracture toughness K1c = 32.3 MPa·m1/2. The yield strength demonstrates anomalous temperature sensitivity with a maximum of 400 °C and at 500 °C. Samples tested at 600 °C show a decrease in yield strength, but a high enough yield point σy ∼400 MPa and a high strengthening rate are very important for high-temperature creep resistance. In creep experiments at a load of 120 MPa at 600 °C, the strain rate varies in the range of 10−7–10−6 s−1, the value of the rate sensitivity n ≈ 4. The main mechanism of creep is dislocation glide.
本研究探讨了粉末直接锻造对铝铁合金 Fe-28 的成分、结构和机械性能的影响。在合成和锻造 Fe3Al 粉末的过程中，在 1100 °C 的温度下形成了均匀的 A2 相。锻造后的孔隙率为 2-2.5%。残留孔隙主要呈平面状，位于粉末颗粒的边界。1300 °C退火可改善颗粒间边界的质量，所有样品都表现出跨晶断裂机制。在 1100 °C 下锻造并在 1300 °C 下退火的样品显示出最大强度 σbend = 1050 MPa 和断裂韧性 K1c = 32.3 MPa-m1/2。屈服强度显示出异常的温度敏感性，在 400 °C 和 500 °C 时达到最大值。在 600 °C 下测试的样品屈服强度有所下降，但足够高的屈服点 σy ∼400 MPa 和高强化率对高温抗蠕变性非常重要。在 600 °C、载荷为 120 兆帕的蠕变实验中，应变速率的变化范围为 10-7-10-6 s-1，速率灵敏度 n ≈ 4。蠕变的主要机制是位错滑行。
{"title":"Mechanical behavior of powdered iron aluminide Fe – 28Al manufactured by direct powder forging","authors":"Oleksandr Tolochyn, Oleksandra Tolochyna, Gennadii Bagliuk, Yan Yevych, Vitalii Danylenko, Yury Podrezov","doi":"10.1016/j.intermet.2024.108537","DOIUrl":"10.1016/j.intermet.2024.108537","url":null,"abstract":"<div><div>This study examines the impact of direct powder forging of powders on the composition, structure, and mechanical properties of iron aluminide Fe–28 at. % Al. During the synthesis and forging of Fe<sub>3</sub>Al powders, a homogeneous A2 phase is formed at a temperature of 1100 °C. Porosity after forging is 2–2.5 %. Residual pores are predominantly planar in shape and are located at the boundaries of the powder particles. Annealing at 1300 °C improves the quality of interparticle boundaries and all samples exhibit transcrystalline fracture mechanism. Samples forged at 1100 °C and annealed at 1300 °C show maximum strength σ<sub>bend</sub> = 1050 MPa and fracture toughness K<sub>1c</sub> = 32.3 MPa·m<sup>1/2</sup>. The yield strength demonstrates anomalous temperature sensitivity with a maximum of 400 °C and at 500 °C. Samples tested at 600 °C show a decrease in yield strength, but a high enough yield point σ<sub>y</sub> ∼400 MPa and a high strengthening rate are very important for high-temperature creep resistance. In creep experiments at a load of 120 MPa at 600 °C, the strain rate varies in the range of 10<sup>−7</sup>–10<sup>−6</sup> s<sup>−1</sup>, the value of the rate sensitivity n ≈ 4. The main mechanism of creep is dislocation glide.</div></div>","PeriodicalId":331,"journal":{"name":"Intermetallics","volume":"175 ","pages":"Article 108537"},"PeriodicalIF":4.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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