Mg-Gd based alloys are an important class of high-performance Mg alloys. In this study, three Mg-Gd alloys with different gadolinium (Gd) contents: Mg-9.54Gd-0.40Zr (wt.%, G10 K), Mg-15.11Gd-0.35Zr (wt.%, G15 K) and Mg-19.67Gd-0.33Zr (wt.%, G20 K) were prepared by semicontinuous casting and subsequent solution and aging heat treatments. The role of Gd content on microstructures and mechanical properties of the Mg-Gd-Zr alloy is studied. All three as-cast alloys exhibit eutectic phases of Mg5Gd, with the amount increasing as the Gd content rises. Mg5Gd disappears after the solution heat treatment (the G10 K alloy solution-treated at 480 °C for 4 h, the G15 K alloy at 500 °C for 12 h and the G20 K alloy at 520 °C for 24 h, respectively). Aging heat treatment at 200 °C for 64 h after solution introduces numerous prismatic β′ precipitates, with a significant increase in their area number density corresponding to increased Gd content. Additionally, the morphology of the β′ precipitates exhibits distinct variations: the G10 K alloy is characterized by an enhanced aspect ratio. Consequently, the peak-aged G10 K alloy demonstrates superior strength-ductility synergy, with a yield strength (YS) of 216 ± 1 MPa, an ultimate tensile strength (UTS) of 363 ± 1 MPa, and an elongation (EL) of 8.7 ± 0.6 %. This study suggests that plasticity diminishes and precipitation strengthening is limited when the gadolinium content exceeds 15 wt.%.
镁钆基合金是一类重要的高性能镁合金。本研究采用了三种不同钆（Gd）含量的镁钆合金：通过半连续铸造以及随后的固溶和时效热处理，制备了三种不同钆（Gd）含量的镁钆合金：Mg-9.54Gd-0.40Zr（重量百分比，G10 K）、Mg-15.11Gd-0.35Zr（重量百分比，G15 K）和 Mg-19.67Gd-0.33Zr（重量百分比，G20 K）。研究了钆含量对 Mg-Gd-Zr 合金微观结构和机械性能的影响。所有三种铸造合金都呈现出 Mg5Gd 共晶相，且随着 Gd 含量的增加而增加。Mg5Gd 在固溶热处理后消失（G10 K 合金分别在 480 ℃ 固溶处理 4 小时，G15 K 合金在 500 ℃ 固溶处理 12 小时，G20 K 合金在 520 ℃ 固溶处理 24 小时）。固溶后在 200 °C 下进行 64 小时的时效热处理会产生大量棱柱形 β′ 沉淀，其面积数密度会随着钆含量的增加而显著增加。此外，β′沉淀的形态也有明显的变化：G10 K 合金的特征是长宽比增大。因此，峰值时效 G10 K 合金显示出卓越的强度-电导率协同作用，屈服强度（YS）为 216 ± 1 MPa，极限拉伸强度（UTS）为 363 ± 1 MPa，伸长率（EL）为 8.7 ± 0.6 %。这项研究表明，当钆含量超过 15 wt.% 时，塑性减弱，沉淀强化受到限制。
{"title":"Effect of Gd content on microstructure and mechanical properties of Mg-xGd-Zr alloys via semicontinuous casting","authors":"Qianye Wu, Yujuan Wu, Qingchen Deng, Chenyang Ding, Yu Zhang, Nanxi Peng, Licheng Jia, Zhiyu Chang, Liming Peng","doi":"10.1016/j.jma.2024.10.013","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.013","url":null,"abstract":"Mg-Gd based alloys are an important class of high-performance Mg alloys. In this study, three Mg-Gd alloys with different gadolinium (Gd) contents: Mg-9.54Gd-0.40Zr (wt.%, G10 K), Mg-15.11Gd-0.35Zr (wt.%, G15 K) and Mg-19.67Gd-0.33Zr (wt.%, G20 K) were prepared by semicontinuous casting and subsequent solution and aging heat treatments. The role of Gd content on microstructures and mechanical properties of the Mg-Gd-Zr alloy is studied. All three as-cast alloys exhibit eutectic phases of Mg<sub>5</sub>Gd, with the amount increasing as the Gd content rises. Mg<sub>5</sub>Gd disappears after the solution heat treatment (the G10 K alloy solution-treated at 480 °C for 4 h, the G15 K alloy at 500 °C for 12 h and the G20 K alloy at 520 °C for 24 h, respectively). Aging heat treatment at 200 °C for 64 h after solution introduces numerous prismatic β′ precipitates, with a significant increase in their area number density corresponding to increased Gd content. Additionally, the morphology of the β′ precipitates exhibits distinct variations: the G10 K alloy is characterized by an enhanced aspect ratio. Consequently, the peak-aged G10 K alloy demonstrates superior strength-ductility synergy, with a yield strength (YS) of 216 ± 1 MPa, an ultimate tensile strength (UTS) of 363 ± 1 MPa, and an elongation (EL) of 8.7 ± 0.6 %. This study suggests that plasticity diminishes and precipitation strengthening is limited when the gadolinium content exceeds 15 wt.%.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"19 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The process of room temperature rolling is a straightforward and efficient method for producing high strength Mg-Li alloys, but the underlying strengthening mechanism remains unclear. In this study, we successfully enhanced the tensile properties of a novel dual-phase Mg-Li alloy through room temperature rolling, with a remarkable yield strength of 201 MPa and an elongation-to-failure of 14 %. Microhardness testing was conducted to evaluate the contribution of the Mg- and Li- phases to the improvement in strength. The results demonstrate that the hardness of Mg-phase reaches 60 HV, which is significantly higher than the 49 HV observed in Li-phase, indicating that the Mg-phase after rolling plays a pivotal role in enhancing material strength. The presence of a high density of dislocations stored in the Mg-phase emerges as the dominant factor contributing to improved strength in Mg-Li alloys. In-situ compression testing reveals that 〈c + a〉 slip activation and twinning-induced slip serve as internal mechanisms for continuous deformation and hardening within the Mg-phase. Despite numerous precipitated Mg-phase particles within the Li-phase matrix, the hardness analysis reveals minimal strain-induced phase transformation effects on the overall strength of the Al-free and Zn-free Mg-Li alloy. These findings provide valuable insights for designing and fabricating high-strength dual-phase Mg-Li alloys.
{"title":"Strengthening of Mg-Li alloy dominated by continuously hardened Mg phase during room temperature rolling","authors":"Zhonghao Heng, Xianzhe Shi, Lijuan Huang, Biao Chen, Jianghua Shen","doi":"10.1016/j.jma.2024.10.002","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.002","url":null,"abstract":"The process of room temperature rolling is a straightforward and efficient method for producing high strength Mg-Li alloys, but the underlying strengthening mechanism remains unclear. In this study, we successfully enhanced the tensile properties of a novel dual-phase Mg-Li alloy through room temperature rolling, with a remarkable yield strength of 201 MPa and an elongation-to-failure of 14 %. Microhardness testing was conducted to evaluate the contribution of the Mg- and Li- phases to the improvement in strength. The results demonstrate that the hardness of Mg-phase reaches 60 HV, which is significantly higher than the 49 HV observed in Li-phase, indicating that the Mg-phase after rolling plays a pivotal role in enhancing material strength. The presence of a high density of dislocations stored in the Mg-phase emerges as the dominant factor contributing to improved strength in Mg-Li alloys. In-situ compression testing reveals that 〈<em>c</em> + <em>a</em>〉 slip activation and twinning-induced slip serve as internal mechanisms for continuous deformation and hardening within the Mg-phase. Despite numerous precipitated Mg-phase particles within the Li-phase matrix, the hardness analysis reveals minimal strain-induced phase transformation effects on the overall strength of the Al-free and Zn-free Mg-Li alloy. These findings provide valuable insights for designing and fabricating high-strength dual-phase Mg-Li alloys.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"7 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Integrating a heterogeneous structure can significantly enhance the strength-ductility synergy of composites. However, the relationship between hetero-deformation induced (HDI) strain hardening and dislocation activity caused by heterogeneous structures in the magnesium matrix composite remains unclear. In this study, a dual-heterogeneous TiC/AZ61 composite exhibits significantly improved plastic elongation (PEL) by nearly one time compared to uniform FG composite, meanwhile maintaining a high strength (UTS: 417 MPa). This is because more severe deformation inhomogeneity in heterogeneous structure leads to more geometrically necessary dislocations (GNDs) accumulation and stronger HDI stress, resulting in higher HDI hardening compared to FG and CG composites. During the early stage of plastic deformation, the pile-up types of GND in the FG zone and CG zone are significantly different. GNDs tend to form substructures in the FG zone instead of the CG zone. They only accumulate at grain boundaries of the CG region, thereby leading to obviously increased back stress in the CG region. In the late deformation stage, the elevated HDI stress activates the new 〈c + a〉 dislocations in the CG region, resulting in dislocation entanglements and even the formation of substructures, further driving the high hardening in the heterogeneous composite. However, For CG composite, 〈c + a〉 dislocations are not activated even under large plastic strains, and only 〈a〉 dislocations pile up at grain boundaries and twin boundaries. Our work provides an in-depth understanding of dislocation variation and HDI hardening in heterogeneous magnesium-based composites.
{"title":"Revealing Hetero-Deformation Induced (HDI) Hardening and Dislocation Activity in a Dual-Heterostructure Magnesium Matrix Composite","authors":"Lingling Fan, Ran Ni, Lingbao Ren, Peng Xiao, Ying Zeng, Dongdi Yin, Hajo Dieringa, Yuanding Huang, Gaofeng Quan, Wei Feng","doi":"10.1016/j.jma.2024.10.012","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.012","url":null,"abstract":"Integrating a heterogeneous structure can significantly enhance the strength-ductility synergy of composites. However, the relationship between hetero-deformation induced (HDI) strain hardening and dislocation activity caused by heterogeneous structures in the magnesium matrix composite remains unclear. In this study, a dual-heterogeneous TiC/AZ61 composite exhibits significantly improved plastic elongation (PEL) by nearly one time compared to uniform FG composite, meanwhile maintaining a high strength (UTS: 417 MPa). This is because more severe deformation inhomogeneity in heterogeneous structure leads to more geometrically necessary dislocations (GNDs) accumulation and stronger HDI stress, resulting in higher HDI hardening compared to FG and CG composites. During the early stage of plastic deformation, the pile-up types of GND in the FG zone and CG zone are significantly different. GNDs tend to form substructures in the FG zone instead of the CG zone. They only accumulate at grain boundaries of the CG region, thereby leading to obviously increased back stress in the CG region. In the late deformation stage, the elevated HDI stress activates the new 〈<em>c + a〉</em> dislocations in the CG region, resulting in dislocation entanglements and even the formation of substructures, further driving the high hardening in the heterogeneous composite. However, For CG composite, 〈<em>c + a〉</em> dislocations are not activated even under large plastic strains, and only 〈<em>a〉</em> dislocations pile up at grain boundaries and twin boundaries. Our work provides an in-depth understanding of dislocation variation and HDI hardening in heterogeneous magnesium-based composites.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"152 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, microstructure and mechanical properties of Mg weld with addition of carbon nanotubes (CNTs) and TiC particles were investigated. The results showed that the weld microstructure was mainly presented as equiaxed grains with almost high angle grain boundaries. The introduction of reinforcements promoted the formation of precipitates and refined the grains effectively, the average grain size was refined by 51 % and 23 % with addition of CNTs and TiC particles, respectively. The dislocation density and the fraction of CSL boundaries were increased with addition of CNTs, while those were decreased with addition of TiC particles. Besides, the infrequent {103} contraction twins formed within the weld due to the stress concentration caused by dislocation accumulation, which contributed to the Σ29 CSL boundary. The ultimate tensile strength and elongation rate were increased by 13.5 % and 40 % with addition of CNTs, while the ultimate tensile strength and micro-hardness were increased by 14.8 % and 20.9 % with addition of TiC particles.
{"title":"Grain refinement, twin formation and mechanical properties of magnesium welds with addition of CNTs and TiC particles","authors":"Yongkang Gao, Lianyong Xu, Kangda Hao, Yongdian Han, Lei Zhao, Wenjing Ren","doi":"10.1016/j.jma.2024.10.009","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.009","url":null,"abstract":"In this work, microstructure and mechanical properties of Mg weld with addition of carbon nanotubes (CNTs) and TiC particles were investigated. The results showed that the weld microstructure was mainly presented as equiaxed grains with almost high angle grain boundaries. The introduction of reinforcements promoted the formation of precipitates and refined the grains effectively, the average grain size was refined by 51 % and 23 % with addition of CNTs and TiC particles, respectively. The dislocation density and the fraction of CSL boundaries were increased with addition of CNTs, while those were decreased with addition of TiC particles. Besides, the infrequent {10<span><span style=\"\"></span><span data-mathml='<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mover accent=\"true\" is=\"true\"><mn is=\"true\">1</mn><mo is=\"true\">&#xAF;</mo></mover></math>' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"><svg aria-hidden=\"true\" focusable=\"false\" height=\"2.202ex\" role=\"img\" style=\"vertical-align: -0.235ex;\" viewbox=\"0 -846.5 570.5 947.9\" width=\"1.325ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"><g is=\"true\"><g is=\"true\" transform=\"translate(35,0)\"><use xlink:href=\"#MJMAIN-31\"></use></g><g is=\"true\" transform=\"translate(0,198)\"><use x=\"-70\" xlink:href=\"#MJMAIN-AF\" y=\"0\"></use><use x=\"70\" xlink:href=\"#MJMAIN-AF\" y=\"0\"></use></g></g></g></svg><span role=\"presentation\"><math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mover accent=\"true\" is=\"true\"><mn is=\"true\">1</mn><mo is=\"true\">¯</mo></mover></math></span></span><script type=\"math/mml\"><math><mover accent=\"true\" is=\"true\"><mn is=\"true\">1</mn><mo is=\"true\">¯</mo></mover></math></script></span>3} contraction twins formed within the weld due to the stress concentration caused by dislocation accumulation, which contributed to the Σ29 CSL boundary. The ultimate tensile strength and elongation rate were increased by 13.5 % and 40 % with addition of CNTs, while the ultimate tensile strength and micro-hardness were increased by 14.8 % and 20.9 % with addition of TiC particles.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"10 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142600883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2024-11-12DOI: 10.1016/j.jma.2024.10.004
X.Z. Jin, G.J. Yang, Xinyu Xu, D.B. Shan, B. Guo, B.B. He, C. Fan, W.C. Xu
The work aims to investigate the formation and transformation mechanism of non-basal texture in the extruded Mg alloys. With this purpose a pure Mg as reference and eight Mg-Gd binary alloys with the Gd concentration ranging from 0.5 wt.% to 18 wt.% were prepared for extrusion. This study shows that the basal fiber texture in pure Mg transited into RE (rare earth) texture in diluted Mg-Gd alloys and into the abnormal C-texture in high-concentration Mg-Gd alloys. In pure Mg, discontinuous dynamic recrystallization plays a predominant role during the extrusion process, resulting in the formation of a typical basal fiber texture. Alloying with high concentration of Gd impedes the dynamic recrystallization process, facilitating the heterogeneous nucleation of shear bands as well as the dynamic recrystallization within shear bands. Dynamic recrystallized grains within shear bands nucleate with a similar orientation to the host deformed parent grains and gradually tilt their c-axis to the extrusion direction during growth by absorbing dislocations, leading to the formation of either the RE-texture orientation or the C-texture orientation, depending on the stored energy within shear bands. The analysis aided by IGMA and TEM characterization reveals that the shear bands originate from the extensive but heterogeneous activation of pyramidal I slip. Tensile tests illustrate a close correlation between the fracture elongation and texture types. A comprehensive understanding of the formation and transformation mechanism of different texture components in Mg alloys holds significant importance for the design of high-performance Mg alloys by texture engineering.
这项工作旨在研究挤压镁合金中非基态纹理的形成和转变机制。为此，以纯镁为参照物，制备了八种镁钆二元合金（钆浓度范围为 0.5 wt.%-18wt.%）进行挤压。研究表明，在稀释的镁钆合金中，纯镁的基底纤维纹理转变为稀土（RE）纹理，而在高浓度镁钆合金中则转变为异常的 C 型纹理。在纯镁中，不连续动态再结晶在挤压过程中起主导作用，从而形成典型的基底纤维纹理。高浓度钆合金阻碍了动态再结晶过程，促进了剪切带的异质成核以及剪切带内的动态再结晶。剪切带内的动态再结晶晶粒的成核取向与寄主变形母晶粒相似，并在生长过程中通过吸收位错使其 c 轴逐渐向挤压方向倾斜，从而形成 RE 纹理取向或 C 纹理取向，具体取决于剪切带内的存储能量。通过 IGMA 和 TEM 表征分析发现，剪切带源于金字塔 I 滑移的广泛但异质的激活。拉伸试验表明，断裂伸长率与纹理类型密切相关。全面了解镁合金中不同纹理成分的形成和转变机制，对于通过纹理工程设计高性能镁合金具有重要意义。
{"title":"On the origin of non-basal texture in extruded Mg-RE alloys and its implication for texture engineering","authors":"X.Z. Jin, G.J. Yang, Xinyu Xu, D.B. Shan, B. Guo, B.B. He, C. Fan, W.C. Xu","doi":"10.1016/j.jma.2024.10.004","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.004","url":null,"abstract":"The work aims to investigate the formation and transformation mechanism of non-basal texture in the extruded Mg alloys. With this purpose a pure Mg as reference and eight Mg-Gd binary alloys with the Gd concentration ranging from 0.5 wt.% to 18 wt.% were prepared for extrusion. This study shows that the basal fiber texture in pure Mg transited into RE (rare earth) texture in diluted Mg-Gd alloys and into the abnormal C-texture in high-concentration Mg-Gd alloys. In pure Mg, discontinuous dynamic recrystallization plays a predominant role during the extrusion process, resulting in the formation of a typical basal fiber texture. Alloying with high concentration of Gd impedes the dynamic recrystallization process, facilitating the heterogeneous nucleation of shear bands as well as the dynamic recrystallization within shear bands. Dynamic recrystallized grains within shear bands nucleate with a similar orientation to the host deformed parent grains and gradually tilt their c-axis to the extrusion direction during growth by absorbing dislocations, leading to the formation of either the RE-texture orientation or the C-texture orientation, depending on the stored energy within shear bands. The analysis aided by IGMA and TEM characterization reveals that the shear bands originate from the extensive but heterogeneous activation of pyramidal I slip. Tensile tests illustrate a close correlation between the fracture elongation and texture types. A comprehensive understanding of the formation and transformation mechanism of different texture components in Mg alloys holds significant importance for the design of high-performance Mg alloys by texture engineering.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"95 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142601112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2024-11-09DOI: 10.1016/j.jma.2024.10.011
Shuai Li, Liuting Zhang, Fuying Wu, Qian Li
Catalytic doping is one of the economic and efficient strategies to optimize the operating temperature and kinetic behavior of magnesium hydride (MgH2). Herein, efficient regulation of electronic and structural rearrangements in niobium-rich nickel oxides was achieved through precise compositional design and niobium cation functionalized doping, thereby greatly enhancing its intrinsic catalytic activity in hydrogen storage systems. As the niobium concentration increased, the Ni-Nb catalysts transformed into a mixed state of multi-phase nanoparticles (composed of nickel and niobium-rich nickel oxides) with smaller particle size and uniform distribution, thus exposing more nucleation sites and diffusion channels at the MgH2/Mg interface. In addition, the additional generation of active Ni-Nb-O mixed phase induced numerous highly topical disordered and distorted crystalline, promoting the transfer and reorganization of H atoms. As a result, a stable and continuous multi-phase/component synergistic catalytic microenvironment could be constructed, exerting remarkable enhancement on MgH2's hydrogen storage performance. After comparative tests, Ni0.7Nb0.3-doped MgH2 presented the optimal low-temperature kinetics with a dehydrogenation activation energy of 78.8 kJ·mol−1. The onset dehydrogenation temperature of MgH2+10 wt% Ni0.7Nb0.3 was reduced to 198 °C and 6.18 wt% H2 could be released at 250 °C within 10 min. In addition, the dehydrogenated MgH2NiNb composites absorbed 4.87 wt% H2 in 10 min at 125 °C and a capacity retention rate was maintained at 6.18 wt% even after 50 reaction cycles. In a word, our work supplies fresh insights for designing novel defective-state multiphase catalysts for hydrogen storage and other energy related field.
{"title":"Cation-induced topical disordered niobium nickel oxide for robust hydrogen storage in magnesium hydride","authors":"Shuai Li, Liuting Zhang, Fuying Wu, Qian Li","doi":"10.1016/j.jma.2024.10.011","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.011","url":null,"abstract":"Catalytic doping is one of the economic and efficient strategies to optimize the operating temperature and kinetic behavior of magnesium hydride (MgH<sub>2</sub>). Herein, efficient regulation of electronic and structural rearrangements in niobium-rich nickel oxides was achieved through precise compositional design and niobium cation functionalized doping, thereby greatly enhancing its intrinsic catalytic activity in hydrogen storage systems. As the niobium concentration increased, the Ni-Nb catalysts transformed into a mixed state of multi-phase nanoparticles (composed of nickel and niobium-rich nickel oxides) with smaller particle size and uniform distribution, thus exposing more nucleation sites and diffusion channels at the MgH<sub>2</sub>/Mg interface. In addition, the additional generation of active Ni-Nb-O mixed phase induced numerous highly topical disordered and distorted crystalline, promoting the transfer and reorganization of H atoms. As a result, a stable and continuous multi-phase/component synergistic catalytic microenvironment could be constructed, exerting remarkable enhancement on MgH<sub>2</sub>'s hydrogen storage performance. After comparative tests, Ni<sub>0.7</sub>Nb<sub>0.3</sub>-doped MgH<sub>2</sub> presented the optimal low-temperature kinetics with a dehydrogenation activation energy of 78.8 kJ·mol<sup>−1</sup>. The onset dehydrogenation temperature of MgH<sub>2</sub>+10 wt% Ni<sub>0.7</sub>Nb<sub>0.3</sub> was reduced to 198 °C and 6.18 wt% H<sub>2</sub> could be released at 250 °C within 10 min. In addition, the dehydrogenated MgH<sub>2</sub><img alt=\"single bond\" src=\"https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/55/entities/sbnd.gif\" style=\"vertical-align:middle\"/>NiNb composites absorbed 4.87 wt% H<sub>2</sub> in 10 min at 125 °C and a capacity retention rate was maintained at 6.18 wt% even after 50 reaction cycles. In a word, our work supplies fresh insights for designing novel defective-state multiphase catalysts for hydrogen storage and other energy related field.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"105 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2024-11-09DOI: 10.1016/j.jma.2024.10.003
Lu Sun, Feng Li, Jia Yang Zhang, Wen Tao Niu, Mu Zi Cao
In this paper, the work hardening and softening behavior of AZ31 magnesium alloy sheets by hard plate accumulative roll bonding (HP-ARB) process in a specific temperature range was studied for the first time, and the cyclic stress relaxation test, EBSD, TEM and other characterization methods were used. When the rolling temperature is 350 °C, the grain size of magnesium sheets is refined to 4.32 (±0.36) µm on average, and it shows an excellent combination of strength and plasticity. The tensile strength reaches 307 (±8.52) MPa and the elongation is 12.73 (±0.84) %. At this time, the curve of work hardening rate decreases smoothly and the degree of hardening is the lowest, and the amplitude of stress drop Δσp in work softening test is the smallest with the increase of cycle times, which shows that the well coordination between work hardening and softening behavior has been achieved. Research has found that the combined effect of grain boundary strengthening and fine grain strengthening enhances the yield and tensile strength of magnesium sheets after three passes HP-ARB process at 350 °C. This is attributed to the high degree of dislocation slip opening in the pyramidal surface 〈a〉 and 〈c + a〉, which not only coordinates the c-axis strain of the entire grain, but also promotes the slip transfer of dislocations in the fine-grained region, significantly improving the elongation of the sheets. This study provides a new idea for the forming and manufacturing of high performance magnesium alloy sheets.
{"title":"Mechanism of work hardening and softening behavior of AZ31 magnesium alloy sheets with hard plate accumulative roll bonding","authors":"Lu Sun, Feng Li, Jia Yang Zhang, Wen Tao Niu, Mu Zi Cao","doi":"10.1016/j.jma.2024.10.003","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.003","url":null,"abstract":"In this paper, the work hardening and softening behavior of AZ31 magnesium alloy sheets by hard plate accumulative roll bonding (HP-ARB) process in a specific temperature range was studied for the first time, and the cyclic stress relaxation test, EBSD, TEM and other characterization methods were used. When the rolling temperature is 350 °C, the grain size of magnesium sheets is refined to 4.32 (±0.36) µm on average, and it shows an excellent combination of strength and plasticity. The tensile strength reaches 307 (±8.52) MPa and the elongation is 12.73 (±0.84) %. At this time, the curve of work hardening rate decreases smoothly and the degree of hardening is the lowest, and the amplitude of stress drop Δσ<sub>p</sub> in work softening test is the smallest with the increase of cycle times, which shows that the well coordination between work hardening and softening behavior has been achieved. Research has found that the combined effect of grain boundary strengthening and fine grain strengthening enhances the yield and tensile strength of magnesium sheets after three passes HP-ARB process at 350 °C. This is attributed to the high degree of dislocation slip opening in the pyramidal surface 〈a〉 and 〈<em>c</em> + <em>a</em>〉, which not only coordinates the c-axis strain of the entire grain, but also promotes the slip transfer of dislocations in the fine-grained region, significantly improving the elongation of the sheets. This study provides a new idea for the forming and manufacturing of high performance magnesium alloy sheets.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"45 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142597025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2024-11-07DOI: 10.1016/j.jma.2024.10.007
Le Zhou, Guiyuan Ren, Tianqi Huang, Zhi Wang, Feng Wang, Ziqi Wei, Pingli Mao, Zheng Liu
In this study, the twinning–detwinning behavior and slip behavior of rolled AZ31 magnesium-alloy plates during a three-step intermittent dynamic compression process along the rolling direction (RD) and normal direction (ND), are investigated via quasi-in situ electron backscatter diffraction, and the causes of the twinning and detwinning behavior are explained according to Schmid law, local strain coordination, and slip trajectories. It is found that the twins are first nucleated and grow at a compressive strain of 3% along the RD. In addition to the Schmid factor (SF), the strain coordination factor (m') also influences the selection of the twin variants during the twinning process, resulting in the nucleation of twins with a low SF. During the second and third steps of the application of continuous compressive strains with magnitudes and directions of 3%RD+3%ND and 3%RD+3%ND+2.5%ND, detwinning occurs to different extents. The observation of the detwinning behavior reveals that the order in which multiple twins within the same grain undergo complete detwinning is related to Schmid law and the strain concentration, with a low SF and a high strain concentration promoting complete detwinning. The interaction between slip dislocations and twin boundaries in the deformed grains as well as the pinning of dislocations at the tips of the {102} tensile twins with a special structure result in incomplete detwinning. Understanding the microstructural evolution and twinning behavior of magnesium alloys under different deformation geometries is important for the development of high-strength and high-toughness magnesium alloys.
{"title":"Quasi-in situ electron backscatter diffraction analysis of twinning–detwinning behavior in AZ31 magnesium- alloy rolled plates subjected to compression loading in different directions","authors":"Le Zhou, Guiyuan Ren, Tianqi Huang, Zhi Wang, Feng Wang, Ziqi Wei, Pingli Mao, Zheng Liu","doi":"10.1016/j.jma.2024.10.007","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.007","url":null,"abstract":"In this study, the twinning–detwinning behavior and slip behavior of rolled AZ31 magnesium-alloy plates during a three-step intermittent dynamic compression process along the rolling direction (RD) and normal direction (ND), are investigated via quasi-in situ electron backscatter diffraction, and the causes of the twinning and detwinning behavior are explained according to Schmid law, local strain coordination, and slip trajectories. It is found that the twins are first nucleated and grow at a compressive strain of 3% along the RD. In addition to the Schmid factor (SF), the strain coordination factor (<em>m'</em>) also influences the selection of the twin variants during the twinning process, resulting in the nucleation of twins with a low SF. During the second and third steps of the application of continuous compressive strains with magnitudes and directions of 3%RD+3%ND and 3%RD+3%ND+2.5%ND, detwinning occurs to different extents. The observation of the detwinning behavior reveals that the order in which multiple twins within the same grain undergo complete detwinning is related to Schmid law and the strain concentration, with a low SF and a high strain concentration promoting complete detwinning. The interaction between slip dislocations and twin boundaries in the deformed grains as well as the pinning of dislocations at the tips of the {10<span><span><math><mover accent=\"true\" is=\"true\"><mn is=\"true\">1</mn><mo is=\"true\">¯</mo></mover></math></span><script type=\"math/mml\"><math><mover accent=\"true\" is=\"true\"><mn is=\"true\">1</mn><mo is=\"true\">¯</mo></mover></math></script></span>2} tensile twins with a special structure result in incomplete detwinning. Understanding the microstructural evolution and twinning behavior of magnesium alloys under different deformation geometries is important for the development of high-strength and high-toughness magnesium alloys.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"13 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2024-11-04DOI: 10.1016/j.jma.2024.09.008
Chuhao Liu, Di Xie, Yanfei Gao, Xiaodan Zhang, Shengyi Zhong, Huamiao Wang, Ke An, Peter K. Liaw, Yinghong Peng
The microscopic-deformation mechanisms of an extruded magnesium alloy with and without precipitates [Guinier-Preston (GP) zones] subjected to cyclic deformation were investigated by in-situ neutron-diffraction (ND) measurements and crystal-plasticity modeling. The relationship between the macroscopic-cyclic-deformation behavior and the microscopic responses (particularly twinning and detwinning) at the grain level was established. The general deformation-mechanism evolution in the solution-state (ST) sample was similar to that in the peak-aged-state (PA) sample over fatigue cycles. Both samples plastically deformed by extension twinning during compression, and by a sequential process of detwinning and dislocation motion under reverse tension. The main difference is that in the PA sample, the presence of precipitating particles constrains the twinning/detwinning behaviors, which leads to an increase in the participation of dislocation slip in the plastic deformation and then induces a strengthening effect during cyclic loading. Based on the combination of the previous in-situ ND results and crystal-plasticity model, our work provides a comprehensive analysis of the interaction between the precipitation strengthening and twinning/detwinning mechanism under the whole multi-cycle cyclic loading and their effect on the macro- and micro-mechanical behavior of the precipitate-strengthened magnesium alloys.
通过原位中子衍射（ND）测量和晶体塑性建模，研究了有沉淀物和无沉淀物[Guinier-Preston（GP）区]的挤压镁合金在循环变形下的微观变形机制。建立了宏观循环变形行为与晶粒级微观反应（尤其是孪晶和脱晶）之间的关系。在疲劳循环过程中，溶液态（ST）样品的一般变形机制演变与峰值老化态（PA）样品相似。两种样品在压缩过程中都通过拉伸孪晶产生塑性变形，而在反向拉伸过程中则通过连续的脱翅和位错运动产生塑性变形。主要区别在于，在 PA 样品中，沉淀颗粒的存在限制了孪生/脱孪行为，导致位错滑移在塑性变形中的参与度增加，进而在循环加载过程中产生强化效应。结合之前的原位 ND 结果和晶体塑性模型，我们的工作全面分析了在整个多循环周期加载下沉淀强化和孪晶/脱晶机制之间的相互作用，以及它们对沉淀强化镁合金宏观和微观力学行为的影响。
{"title":"Precipitation-strengthened micromechanical behaviors of magnesium alloy under cyclic loading","authors":"Chuhao Liu, Di Xie, Yanfei Gao, Xiaodan Zhang, Shengyi Zhong, Huamiao Wang, Ke An, Peter K. Liaw, Yinghong Peng","doi":"10.1016/j.jma.2024.09.008","DOIUrl":"https://doi.org/10.1016/j.jma.2024.09.008","url":null,"abstract":"The microscopic-deformation mechanisms of an extruded magnesium alloy with and without precipitates [Guinier-Preston (GP) zones] subjected to cyclic deformation were investigated by <em>in-situ</em> neutron-diffraction (ND) measurements and crystal-plasticity modeling. The relationship between the macroscopic-cyclic-deformation behavior and the microscopic responses (particularly twinning and detwinning) at the grain level was established. The general deformation-mechanism evolution in the solution-state (ST) sample was similar to that in the peak-aged-state (PA) sample over fatigue cycles. Both samples plastically deformed by extension twinning during compression, and by a sequential process of detwinning and dislocation motion under reverse tension. The main difference is that in the PA sample, the presence of precipitating particles constrains the twinning/detwinning behaviors, which leads to an increase in the participation of dislocation slip in the plastic deformation and then induces a strengthening effect during cyclic loading. Based on the combination of the previous <em>in-situ</em> ND results and crystal-plasticity model, our work provides a comprehensive analysis of the interaction between the precipitation strengthening and twinning/detwinning mechanism under the whole multi-cycle cyclic loading and their effect on the macro- and micro-mechanical behavior of the precipitate-strengthened magnesium alloys.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"247 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2024-11-02DOI: 10.1016/j.jma.2024.10.008
Z.Y. Xu, Y.Q. You, Q. Lu, C.J. Li, M. Song, J. Tan, L. Liu, X.F. Chen, J.H. Yi
Many properties of Mg matrix composites are mutually incompatible, and even completely repel each other. Here, we constructed a magnetic layered component in Mg matrix composite reinforced with reduced graphene oxide (RGO) through an in-situ interface reaction strategy, achieving simultaneous improvement in the strength, ductility, and electromagnetic shielding performance of the composite. The magnetic component is generated by the in-situ reaction of Fe2O3 nanoparticles encapsulated on RGO with the Mg matrix. The superior strength-ductility synergy originates from layered heterostructure, which actives non-basal dislocations and enables a stable microcrack-multiplication. The heterogeneous layered structure strengthens the multi-level reflection of electromagnetic wave (EMW) inside the composite. The in-situ interfacial reaction introduces abundant of heterogeneous interfaces into the composites, which improves the interfacial polarization loss ability of the composites. The magnetic RGO layer can provide shape anisotropy that breaks the Snoek limit, thus improving the magnetic loss ability of composite in high-frequency electromagnetic fields. The synergistic action of multiple EMW loss mechanisms improves the electromagnetic shielding performance of composite. The current study emphasizes the influence of interface structure on the mechanical and functional properties of composites, and presents a promising approach for the development of structure/functional integrated composites with enhanced properties.
{"title":"Breaking Mg matrix composite property trade-offs via in-situ interface reaction and heterogeneous structure design","authors":"Z.Y. Xu, Y.Q. You, Q. Lu, C.J. Li, M. Song, J. Tan, L. Liu, X.F. Chen, J.H. Yi","doi":"10.1016/j.jma.2024.10.008","DOIUrl":"https://doi.org/10.1016/j.jma.2024.10.008","url":null,"abstract":"Many properties of Mg matrix composites are mutually incompatible, and even completely repel each other. Here, we constructed a magnetic layered component in Mg matrix composite reinforced with reduced graphene oxide (RGO) through an in-situ interface reaction strategy, achieving simultaneous improvement in the strength, ductility, and electromagnetic shielding performance of the composite. The magnetic component is generated by the in-situ reaction of Fe<sub>2</sub>O<sub>3</sub> nanoparticles encapsulated on RGO with the Mg matrix. The superior strength-ductility synergy originates from layered heterostructure, which actives non-basal dislocations and enables a stable microcrack-multiplication. The heterogeneous layered structure strengthens the multi-level reflection of electromagnetic wave (EMW) inside the composite. The in-situ interfacial reaction introduces abundant of heterogeneous interfaces into the composites, which improves the interfacial polarization loss ability of the composites. The magnetic RGO layer can provide shape anisotropy that breaks the Snoek limit, thus improving the magnetic loss ability of composite in high-frequency electromagnetic fields. The synergistic action of multiple EMW loss mechanisms improves the electromagnetic shielding performance of composite. The current study emphasizes the influence of interface structure on the mechanical and functional properties of composites, and presents a promising approach for the development of structure/functional integrated composites with enhanced properties.","PeriodicalId":16214,"journal":{"name":"Journal of Magnesium and Alloys","volume":"145 1","pages":""},"PeriodicalIF":17.6,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142566060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
NiNb composites absorbed 4.87 wt% H2 in 10 min at 125 °C and a capacity retention rate was maintained at 6.18 wt% even after 50 reaction cycles. In a word, our work supplies fresh insights for designing novel defective-state multiphase catalysts for hydrogen storage and other energy related field.
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