Pub Date : 2024-12-02DOI: 10.1016/j.scriptamat.2024.116481
Peisen Lv , Lirong Liu , Zhangrui Zhou , Chuntao Ge , Jian Zhang , Yunsong Zhao
Generally, interactions of stacking faults (SF) have been considered to have a strengthening effect for single crystal (SX) superalloys during creep at intermediate temperatures. However, results in this work show that V-like SF interactions are more effective than T- or X-like interaction in preventing further expansion of SFs in the experimental Re-low and Re-free SX superalloys. Under the creep condition of 760 °C/780 MPa, dislocations entanglement near concave γ/γ′ interfaces, enrichment of Re atoms along SFs and more V-like SF interactions within γ′ phase are conductive to lowering the creep rate of the Re-low alloy. Finally, based on interface and two-phase evolution, configurations of matrix dislocations as well as the expansion and interactions of SFs, we propose new understandings to improve intermediate-temperature creep resistance for SX superalloys.
{"title":"Insights in improving creep resistance of low-cost 2nd-generation nickel based single crystal superalloys at intermediate temperature","authors":"Peisen Lv , Lirong Liu , Zhangrui Zhou , Chuntao Ge , Jian Zhang , Yunsong Zhao","doi":"10.1016/j.scriptamat.2024.116481","DOIUrl":"10.1016/j.scriptamat.2024.116481","url":null,"abstract":"<div><div>Generally, interactions of stacking faults (SF) have been considered to have a strengthening effect for single crystal (SX) superalloys during creep at intermediate temperatures. However, results in this work show that V-like SF interactions are more effective than T- or X-like interaction in preventing further expansion of SFs in the experimental <em>Re</em>-low and <em>Re</em>-free SX superalloys. Under the creep condition of 760 °C/780 MPa, dislocations entanglement near concave γ/γ′ interfaces, enrichment of <em>Re</em> atoms along SFs and more V-like SF interactions within γ′ phase are conductive to lowering the creep rate of the <em>Re</em>-low alloy. Finally, based on interface and two-phase evolution, configurations of matrix dislocations as well as the expansion and interactions of SFs, we propose new understandings to improve intermediate-temperature creep resistance for SX superalloys.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116481"},"PeriodicalIF":5.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759521","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 : 2024-12-02DOI: 10.1016/j.scriptamat.2024.116479
Lei Wang , Zhihua Dong , Bin Jiang , Cuihong Wang , Xiaoying Qian , Levente Vitos , Fusheng Pan
Using first principle alloy theory, we calculate the basal stacking fault energies as a function of chemical composition for a series of Mg binary alloys by accounting for the chemical disorder in solid solution. We show that while the basal stacking fault energies significantly increase with the addition of Co, Ni, Ag, and Li, they obviously decline upon alloying with Sn, Y, Ca, and Al. In contrast, Zn and Ti exhibit negligible influence on the basal stacking fault energy of I1 and I2 fault. The varied influence of alloying species on basal stacking fault energies are demonstrated to predominately determined by the volume- and composition-dependent relative phase stability between face-centered cubic and hexagonal close-packed structure. The influence of alloy species predicted in solid solution are obviously different from those computed for segregated ones, underlining the significance of chemical disorder to the intrinsic energy barriers of Mg solid solutions.
{"title":"Influence of non-rare earth elements on basal stacking fault energy of Mg binary alloys in solid solution","authors":"Lei Wang , Zhihua Dong , Bin Jiang , Cuihong Wang , Xiaoying Qian , Levente Vitos , Fusheng Pan","doi":"10.1016/j.scriptamat.2024.116479","DOIUrl":"10.1016/j.scriptamat.2024.116479","url":null,"abstract":"<div><div>Using first principle alloy theory, we calculate the basal stacking fault energies as a function of chemical composition for a series of Mg binary alloys by accounting for the chemical disorder in solid solution. We show that while the basal stacking fault energies significantly increase with the addition of Co, Ni, Ag, and Li, they obviously decline upon alloying with Sn, Y, Ca, and Al. In contrast, Zn and Ti exhibit negligible influence on the basal stacking fault energy of I<sub>1</sub> and I<sub>2</sub> fault. The varied influence of alloying species on basal stacking fault energies are demonstrated to predominately determined by the volume- and composition-dependent relative phase stability between face-centered cubic and hexagonal close-packed structure. The influence of alloy species predicted in solid solution are obviously different from those computed for segregated ones, underlining the significance of chemical disorder to the intrinsic energy barriers of Mg solid solutions.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116479"},"PeriodicalIF":5.3,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759806","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 : 2024-11-30DOI: 10.1016/j.scriptamat.2024.116474
Chunan Li , Calin D. Marioara , Constantinos Hatzoglou , Sigmund J. Andersen , Randi Holmestad , Yanjun Li
In many industrial Al-Mg-Si alloys, natural aging (NA) has a detrimental effect on the age-hardening response during artificial aging (AA), due to the formation of unfavorable nanometer-sized solute clusters during NA. In this work, we systematically studied the atomic structures of solute clusters formed in a dilute 6060 alloy and a more concentrated 6082 alloy after 1-year NA and their influences on the age hardening behavior during the following AA. In 6060, it was found that NA promotes the formation of high-density solute clusters in the form of GP-zones composed of 1–3 β″-eyes, which can act as precursors of β″ precipitates, enhancing the age-hardening kinetics during AA. In contrast, most solute clusters in 6082 after 1-year NA are 1β″-eye, binocular and square GP-zones, while GP-zones containing multiple β″-eyes are rare. As a result, NA has a strong negative effect on the age-hardening response during AA and the peak-aged strength.
{"title":"Chemical composition dependent atom clustering during natural aging in Al-Mg-Si alloys","authors":"Chunan Li , Calin D. Marioara , Constantinos Hatzoglou , Sigmund J. Andersen , Randi Holmestad , Yanjun Li","doi":"10.1016/j.scriptamat.2024.116474","DOIUrl":"10.1016/j.scriptamat.2024.116474","url":null,"abstract":"<div><div>In many industrial Al-Mg-Si alloys, natural aging (NA) has a detrimental effect on the age-hardening response during artificial aging (AA), due to the formation of unfavorable nanometer-sized solute clusters during NA. In this work, we systematically studied the atomic structures of solute clusters formed in a dilute 6060 alloy and a more concentrated 6082 alloy after 1-year NA and their influences on the age hardening behavior during the following AA. In 6060, it was found that NA promotes the formation of high-density solute clusters in the form of GP-zones composed of 1–3 β″-eyes, which can act as precursors of β″ precipitates, enhancing the age-hardening kinetics during AA. In contrast, most solute clusters in 6082 after 1-year NA are 1β″-eye, binocular and square GP-zones, while GP-zones containing multiple β″-eyes are rare. As a result, NA has a strong negative effect on the age-hardening response during AA and the peak-aged strength.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116474"},"PeriodicalIF":5.3,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748256","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 : 2024-11-30DOI: 10.1016/j.scriptamat.2024.116480
Yifan Wu , Jingzi Zhang , Chengquan Zhong , Jiakai Liu , Kailong Hu , Xi Lin
The creep behavior of steels is influenced by factors such as lattice structure, defects, and stress conditions. Given the high cost and time required for creep tests, accurately predicting creep life and minimum creep rate is essential. This study analyzed 9–12% chromium (Cr) steel using a dataset of 1496 entries covering material composition, mechanical properties, minimum creep rate, and creep life. Nine machine learning (ML) models were developed, with the artificial neural network (ANN) achieving the highest prediction accuracy, evidenced by a coefficient of determination (R2) of 0.9973 and a root mean square error (RMSE) of 0.045. A dual-target neural network model provided R2 values of 0.9853 for creep life and 0.9838 for minimum creep rate. Additionally, an empirical equation based on gene expression programming (GEP) achieved an R2 exceeding 0.9741. This study offers novel insights into the design of 9–12% Cr steel with enhanced creep life.
{"title":"Machine learning-assisted creep life prediction and empirical formula generation for 9-12% Cr steel","authors":"Yifan Wu , Jingzi Zhang , Chengquan Zhong , Jiakai Liu , Kailong Hu , Xi Lin","doi":"10.1016/j.scriptamat.2024.116480","DOIUrl":"10.1016/j.scriptamat.2024.116480","url":null,"abstract":"<div><div>The creep behavior of steels is influenced by factors such as lattice structure, defects, and stress conditions. Given the high cost and time required for creep tests, accurately predicting creep life and minimum creep rate is essential. This study analyzed 9–12% chromium (Cr) steel using a dataset of 1496 entries covering material composition, mechanical properties, minimum creep rate, and creep life. Nine machine learning (ML) models were developed, with the artificial neural network (ANN) achieving the highest prediction accuracy, evidenced by a coefficient of determination (<em>R</em><sup>2</sup>) of 0.9973 and a root mean square error (RMSE) of 0.045. A dual-target neural network model provided <em>R</em><sup>2</sup> values of 0.9853 for creep life and 0.9838 for minimum creep rate. Additionally, an empirical equation based on gene expression programming (GEP) achieved an <em>R</em><sup>2</sup> exceeding 0.9741. This study offers novel insights into the design of 9–12% Cr steel with enhanced creep life.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116480"},"PeriodicalIF":5.3,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748257","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 : 2024-11-28DOI: 10.1016/j.scriptamat.2024.116477
Lipeng Ding , Yaru Ning , Qingbo Yang , Yaoyao Weng , Chenglin Wang , Zhihong Jia
The thickening behavior of T1 precipitates in an over-aged Al-Cu-Li alloy was studied using high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy (EDX) and first-principles calculation. This study revealed four distinct T1 thickening mechanisms occur in the Al-Cu-Li alloy during long-term over-aging. The most prevalent mechanism, designated Type-I, is featured by a shared Al/Li layer in-between two T1 units. In contrast, Type-II and Type-IV involve two separated Al/Li layers with different misalignments, while the Type-III involves the insertion of a Cu-layer in-between two separated T1 units. These four different thickening processes can coexist and interconvert, resulting in diverse T1 precipitate configurations. The multiple T1 thickening mechanisms can regulate the lattice misfit of the T1/Al matrix interface, which potentially affect the strengthening and thermal stability of the T1 phase.
利用高角度环形暗场扫描透射电子显微镜（HAADF-STEM）、能量色散 X 射线光谱（EDX）和第一原理计算，研究了超时效铝-铜-锂合金中 T1 沉淀的增厚行为。这项研究揭示了铝-铜-锂合金在长期超时效过程中出现的四种不同的 T1 增厚机制。最普遍的机制被称为 I 型，其特点是在两个 T1 单元之间有一个共享的 Al/Li 层。相比之下，II 型和 IV 型涉及两个错位分离的铝/锂层，而 III 型涉及在两个分离的 T1 单元之间插入一个铜层。这四种不同的增厚过程可以共存和相互转换，从而形成不同的 T1 沉淀构型。多种 T1 增厚机制可以调节 T1/Al 基体界面的晶格错位，从而可能影响 T1 相的强化和热稳定性。
{"title":"New insights into multiple thickening mechanisms of T1 precipitates in Al-Cu-Li alloys","authors":"Lipeng Ding , Yaru Ning , Qingbo Yang , Yaoyao Weng , Chenglin Wang , Zhihong Jia","doi":"10.1016/j.scriptamat.2024.116477","DOIUrl":"10.1016/j.scriptamat.2024.116477","url":null,"abstract":"<div><div>The thickening behavior of T<sub>1</sub> precipitates in an over-aged Al-Cu-Li alloy was studied using high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy (EDX) and first-principles calculation. This study revealed four distinct T<sub>1</sub> thickening mechanisms occur in the Al-Cu-Li alloy during long-term over-aging. The most prevalent mechanism, designated Type-I, is featured by a shared Al/Li layer in-between two T<sub>1</sub> units. In contrast, Type-II and Type-IV involve two separated Al/Li layers with different misalignments, while the Type-III involves the insertion of a Cu-layer in-between two separated T<sub>1</sub> units. These four different thickening processes can coexist and interconvert, resulting in diverse T<sub>1</sub> precipitate configurations. The multiple T<sub>1</sub> thickening mechanisms can regulate the lattice misfit of the T<sub>1</sub>/Al matrix interface, which potentially affect the strengthening and thermal stability of the T<sub>1</sub> phase.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116477"},"PeriodicalIF":5.3,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720406","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 : 2024-11-27DOI: 10.1016/j.scriptamat.2024.116476
Muchi Jiang , Hao Jiang , Rui Xi , Dechun Ren , Haibin Ji , Jiafeng Lei , Xiebin Wang
In this work, we found that the long strip-like Ti4Ni2Ox phase, concentrated at the grain boundaries (GBs), is the primary reason for the inferior superelasticity of laser powder bed fusion (L-PBF) fabricated NiTi alloys. In order to improve the superelasticity of L-PBF produced NiTi alloy, we proposed a simple yet efficient heat treatment protocol, which includes solution treatment at 1273 K for 3 h and subsequent aging treatment at 623 K for 0.5 h. The solution treatment leads to the spheroidization and coarsening of the Ti4Ni2Ox phase, as well as the growth of NiTi grains. The grain growth captures Ti4Ni2Ox phase at GBs into the grain interior, which improves largely the integrity of the matrix. Aging treatment introduces Ni4Ti3 nanoprecipiates, which could improve the stability of superelasiticity. As a result, NiTi alloy with excellent superelasticity is obtained, which shows a recovery rate of >80 % (pre-strian of 5 %) after 317 cycles.
{"title":"Superior superelasticity of laser powder bed fusion fabricated NiTi alloys achieved by post heat treatment","authors":"Muchi Jiang , Hao Jiang , Rui Xi , Dechun Ren , Haibin Ji , Jiafeng Lei , Xiebin Wang","doi":"10.1016/j.scriptamat.2024.116476","DOIUrl":"10.1016/j.scriptamat.2024.116476","url":null,"abstract":"<div><div>In this work, we found that the long strip-like Ti<sub>4</sub>Ni<sub>2</sub>O<em><sub>x</sub></em> phase, concentrated at the grain boundaries (GBs), is the primary reason for the inferior superelasticity of laser powder bed fusion (L-PBF) fabricated NiTi alloys. In order to improve the superelasticity of L-PBF produced NiTi alloy, we proposed a simple yet efficient heat treatment protocol, which includes solution treatment at 1273 K for 3 h and subsequent aging treatment at 623 K for 0.5 h. The solution treatment leads to the spheroidization and coarsening of the Ti<sub>4</sub>Ni<sub>2</sub>O<em><sub>x</sub></em> phase, as well as the growth of NiTi grains. The grain growth captures Ti<sub>4</sub>Ni<sub>2</sub>O<em><sub>x</sub></em> phase at GBs into the grain interior, which improves largely the integrity of the matrix. Aging treatment introduces Ni<sub>4</sub>Ti<sub>3</sub> nanoprecipiates, which could improve the stability of superelasiticity. As a result, NiTi alloy with excellent superelasticity is obtained, which shows a recovery rate of >80 % (pre-strian of 5 %) after 317 cycles.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116476"},"PeriodicalIF":5.3,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720405","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 : 2024-11-26DOI: 10.1016/j.scriptamat.2024.116470
Yarong Wang, Hongchao Kou, Mengyu Jia, Yonghao Yu, Yuqing Li, Jun Wang, Jinshan Li
The effect of the magnetic field heat treatment on the high-temperature α phase orientation for extruded TNM alloy was studied. Results show that the strength of {0001} basal texture ({0001} crystal plane is parallel to the extrusion direction) increased after holding for 30 min at 1290 ℃ under the 10T magnetic field. The main reason is due to the preferred growth of α phases with <11-20> orientation (<11-20> crystal orientation is normal to the extrusion direction) during the holding time and the growth behavior of α phases with <11-20> orientation is related to the magnetic field direction. Preferred growth of α phases with <11-20> orientation is mainly by consuming adjacent α phases with <10-10> orientation during holding time at 1290 ℃ under the 10T magnetic field. If the magnetic field direction is parallel to the extrusion direction, the preferred growth of α phases with <11-20> orientation is attributed to the magnetic field inducing the increasing of grain boundary mobility. If the magnetic field direction is normal to the extrusion direction, the preferred growth of α phases with <11-20> orientation is caused by the magnetic driving force generated in grain boundaries under the 10T magnetic field.
{"title":"Strengthening the {0001} basal texture of α phases for extruded TNM alloy by high magnetic field heat treatment at 1290 ℃","authors":"Yarong Wang, Hongchao Kou, Mengyu Jia, Yonghao Yu, Yuqing Li, Jun Wang, Jinshan Li","doi":"10.1016/j.scriptamat.2024.116470","DOIUrl":"10.1016/j.scriptamat.2024.116470","url":null,"abstract":"<div><div>The effect of the magnetic field heat treatment on the high-temperature α phase orientation for extruded TNM alloy was studied. Results show that the strength of {0001} basal texture ({0001} crystal plane is parallel to the extrusion direction) increased after holding for 30 min at 1290 ℃ under the 10T magnetic field. The main reason is due to the preferred growth of α phases with <11-20> orientation (<11-20> crystal orientation is normal to the extrusion direction) during the holding time and the growth behavior of α phases with <11-20> orientation is related to the magnetic field direction. Preferred growth of α phases with <11-20> orientation is mainly by consuming adjacent α phases with <10-10> orientation during holding time at 1290 ℃ under the 10T magnetic field. If the magnetic field direction is parallel to the extrusion direction, the preferred growth of α phases with <11-20> orientation is attributed to the magnetic field inducing the increasing of grain boundary mobility. If the magnetic field direction is normal to the extrusion direction, the preferred growth of α phases with <11-20> orientation is caused by the magnetic driving force generated in grain boundaries under the 10T magnetic field.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116470"},"PeriodicalIF":5.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142706411","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 : 2024-11-26DOI: 10.1016/j.scriptamat.2024.116468
Bailey E. Rhodes , Pulkit Garg , Nicolò Maria della Ventura , Justin A. Mayer , Irene J. Beyerlein , Daniel S. Gianola
Ordered intermetallic materials are promising candidates for applications in extreme environments due to the strong localized bonding schemes that stabilize the structures against degradation. Here, we investigate the propensity for deformation twinning modes in the L21-ordered MnCu2Al intermetallic by inducing a state of severe plastic deformation. Post-mortem microstructural analysis reveals the presence of meso-scale deformation twins accompanied by a high degree of nano-scale crystalline heterogeneity. The orientation relationship between the parent and twin structures is consistent with activation of the deformation twinning mode. Ab initio generalized stacking fault energy curve calculations corresponding to twinning shear suggest that the magnitude of the twinning partial is and results in the local formation of a metastable orthorhombic phase within the pseudo-twin. This work highlights the discrepancy between the deformation modes of ordered/disordered structures and promotes an increased awareness for the role that long-range chemical order plays in determining deformation modes.
有序金属间化合物具有强大的局部键合机制，可稳定结构，防止降解，因此有望应用于极端环境中。在这里，我们通过诱导严重的塑性变形状态，研究了 L21 有序 MnCu2Al 金属间化合物的变形孪生模式倾向。死后微观结构分析表明，介观尺度变形孪晶的存在伴随着高度纳米尺度的晶体异质性。母体和孪晶结构之间的取向关系与〈111〉{112}变形孪晶模式的激活相一致。与〈111〉{112}孪晶剪切相对应的 Ab initio 广义堆积断层能量曲线计算表明，孪晶部分的大小为 14〈111〉{112}，并导致在伪孪晶内部局部形成可蜕变的正交相。这项研究凸显了有序/无序结构变形模式之间的差异，并促进了对长程化学有序在决定变形模式方面所起作用的认识。
{"title":"Deformation pseudo-twinning of the L21-ordered intermetallic superlattice","authors":"Bailey E. Rhodes , Pulkit Garg , Nicolò Maria della Ventura , Justin A. Mayer , Irene J. Beyerlein , Daniel S. Gianola","doi":"10.1016/j.scriptamat.2024.116468","DOIUrl":"10.1016/j.scriptamat.2024.116468","url":null,"abstract":"<div><div>Ordered intermetallic materials are promising candidates for applications in extreme environments due to the strong localized bonding schemes that stabilize the structures against degradation. Here, we investigate the propensity for deformation twinning modes in the <em>L</em>2<sub>1</sub>-ordered MnCu<sub>2</sub>Al intermetallic by inducing a state of severe plastic deformation. <em>Post-mortem</em> microstructural analysis reveals the presence of meso-scale deformation twins accompanied by a high degree of nano-scale crystalline heterogeneity. The orientation relationship between the parent and twin structures is consistent with activation of the <span><math><mrow><mo>〈</mo><mn>111</mn><mo>〉</mo></mrow><mo>{</mo><mn>112</mn><mo>}</mo></math></span> deformation twinning mode. <em>Ab initio</em> generalized stacking fault energy curve calculations corresponding to <span><math><mo>〈</mo><mn>111</mn><mo>〉</mo><mo>{</mo><mn>112</mn><mo>}</mo></math></span> twinning shear suggest that the magnitude of the twinning partial is <span><math><mfrac><mrow><mn>1</mn></mrow><mrow><mn>4</mn></mrow></mfrac><mo>〈</mo><mn>111</mn><mo>〉</mo><mo>{</mo><mn>112</mn><mo>}</mo></math></span> and results in the local formation of a metastable orthorhombic phase within the pseudo-twin. This work highlights the discrepancy between the deformation modes of ordered/disordered structures and promotes an increased awareness for the role that long-range chemical order plays in determining deformation modes.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116468"},"PeriodicalIF":5.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142706410","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}
Pub Date : 2024-11-25DOI: 10.1016/j.scriptamat.2024.116469
Tianyi Lyu, Yu Zou
In laser powder bed fusion (LPBF), the formation of bulky columnar grains often results in undesirable mechanical anisotropy. Here, we demonstrate a new strategy to control the microstructure in LPBF through tuning melt pool overlaps without changing energy densities and scan patterns. Using 316L stainless steel as an example, we generate a wide range of grain sizes and morphologies. The underlying mechanism is associated with the retainment or elimination of newly nucleated grains at a melt pool during the formation of subsequent melt pools. The propensity of retainment or elimination of grains is largely dependent on the extent of melt pool overlaps because the grains are prone to nucleate at the free-surfaces of melt pool boundaries. This facile strategy could be applicable to a wide range of metallic alloys, paving a new way for microstructure engineering in additive manufacturing.
{"title":"Remelting-based microstructure engineering in laser powder bed fusion: A case study in 316L stainless steel","authors":"Tianyi Lyu, Yu Zou","doi":"10.1016/j.scriptamat.2024.116469","DOIUrl":"10.1016/j.scriptamat.2024.116469","url":null,"abstract":"<div><div>In laser powder bed fusion (LPBF), the formation of bulky columnar grains often results in undesirable mechanical anisotropy. Here, we demonstrate a new strategy to control the microstructure in LPBF through tuning melt pool overlaps without changing energy densities and scan patterns. Using 316L stainless steel as an example, we generate a wide range of grain sizes and morphologies. The underlying mechanism is associated with the retainment or elimination of newly nucleated grains at a melt pool during the formation of subsequent melt pools. The propensity of retainment or elimination of grains is largely dependent on the extent of melt pool overlaps because the grains are prone to nucleate at the free-surfaces of melt pool boundaries. This facile strategy could be applicable to a wide range of metallic alloys, paving a new way for microstructure engineering in additive manufacturing.</div></div>","PeriodicalId":423,"journal":{"name":"Scripta Materialia","volume":"257 ","pages":"Article 116469"},"PeriodicalIF":5.3,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142706379","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}
Pub Date : 2024-11-25DOI: 10.1016/j.scriptamat.2024.116472
Yi Li, Junnan Lin
In a published paper, Acta Mater. 61 (2013) 294–309, Kamimura et al. estimated the Peierls stress of various ceramics and semiconductors based on experimental data by using a dislocation kink-pair theory. This paper shows that their calculated values of Peierls stress are incorrect, being one order of magnitude lower than the corrected values for most materials. Additionally, we assess the validity of the method for estimating the Peierls stress employed Kamimura et al.
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