在100-210℃和150-300 MPa的条件下, 研究了Al-5.3Cu-0.8Mg-0.5Ag-0.3Mn-0.15Zr耐热铝合金的蠕变行为, 探讨了时效状态对合金高温性能的影响. 结果表明: 在相同蠕变条件下, 欠时效态合金的稳态蠕变速率远远低于峰时效态合金. 在210℃/200 MPa下, 欠时效态合金的蠕变断裂时间为75 h, 而峰时效态合金的蠕变断裂时间仅为21 h. 蠕变过程中, 合金中的析出相长大. 峰时效态合金中析出相尺寸的增大速率高于欠时效态合金. 欠时效态合金中还发生了动态析出, 这些细小的析出相在蠕变过程中阻碍了位错的运动, 使得合金蠕变速率降低. 在100-150℃下合金的稳态蠕变速率保持在较低水平. 当温度升高到180℃时, 合金的稳态蠕变速率急剧增大. 合金稳态蠕变速率随着蠕变温度的升高和应力的提高均有增大趋势, 3者之间的关系可用一本构方程来表示, 其表观激活能为102 kJ/mol.

通过改变固溶热处理温度、保温时间和固溶后冷却方式, 研究了不同固溶热处理工艺对一种新型铸造高温合金组织和性能的影响. 结果表明, 将合金在不同温度固溶处理2 h后空冷, 合金在760 ℃, 660 MPa和 980 ℃, 180 MPa条件下的持久寿命随热处理温度的升高先升高而后降低; 固溶处理温度为 1220 ℃时, 760 ℃, 660 MPa条件下的持久寿命达到最高; 固溶处理温度为1180 ℃时, 980 ℃, 180 MPa条件下的持久寿命最高; 当热处理温度从1120 ℃升高到1220 ℃时, 拉伸强度随温度升高而增加, 继续升温到1240 ℃, 拉伸强度下降. 当固溶热处理温度为1120℃, 处理时间在2---8 h范围内变化时, 合金在760 ℃, 660 MPa条件下的持久寿命随时间延长而降低, 而在980 ℃, 180 MPa条件下的持久寿命随处理时间延长而升高; 当热处理时间为2和4 h时, 拉伸强度较高; 延长到6和8 h时, 拉伸强度下降. 当冷却方式不同时, 合金持久性能也发生变化. γ'相和γ/γ'共晶组织在尺寸、形态、分布和数量上的变化是导致合金力学性能变化的关键因素.

AlSi10Mg is a frequently utilized aluminum alloy known for its low density, high specific strength, strong energy absorption capability, and good impact resistance. It holds significant appeal in the aviation, automotive, and machinery sectors and is particularly used as protective structures for critical aerospace components. In particular, in complex application scenarios, these protective structures are often subjected to impacts from foreign objects at different loading rates. This leads to diverse forms of damage and unpredictable damage patterns, ultimately jeopardizing key components and disrupting the normal operation of associated parts. Herein, through extensive research into the preparation, properties, and factors influencing AlSi10Mg porous structures, an understanding of the intrinsic relationship between the porous metal structure and its properties is revealed. This is important for improving material properties, expanding application possibilities, and promoting scientific and technological advancement. Exploring the application potential of AlSi10Mg porous structures across various fields offers theoretical support and technical guidance for its practical utilization. Moreover, this will provide new insights and methodologies for the future development of aluminum alloys with porous structures. By conducting a series of experimental studies, theoretical analyses, and numerical simulations, the load-bearing capacity, damage modes, and damage mechanisms of the optimized AlSi10Mg porous structures under different loading strain rates were examined. The rusults showed that the predominant damage modes in AlSi10Mg porous structures are fracture and shear damages, and the mechanical behavior is unaffected by the loading strain rates. The combination of structural damage analysis and high-precision numerical simulations revealed that under axial compressive loading, the AlSi10Mg porous structures experiences shear damage caused by relative misalignment along the diagonal cross section. This failure mode is the direct cause of the fracture damage of the structure. Furthermore, combined experimental and theoretical analyses indicated that the energy absorption properties of the AlSi10Mg porous structures are maintained at low and medium strain rates when the strain of the structures is less than 10%. When the strain exceeds 10%, the energy absorption properties at medium strain rates slightly improve compared to those at low strain rates. The energy absorption properties of the AlSi10Mg porous structures remain almost unchanged under different strain rates ranging from 378 to 1639 s-1.

为探明AlSi10Mg多孔结构在不同加载应变率条件下的承载能力、破坏模式及破坏机理，展开了一系列实验研究、理论分析和数值模拟。通过实验研究明确了该AlSi10Mg多孔结构的损伤破坏模式主要表现为损伤断裂和剪切破坏，且其力学行为对加载应变率不敏感。结合结构损伤分析和高精度数值模拟研究，发现AlSi10Mg多孔结构在轴向压缩载荷作用下沿斜截面相对错动而发生剪切破坏，这一失效模式是导致其结构发生断裂破坏的最直接原因。结合实验研究和理论分析表明，当AlSi10Mg多孔结构应变小于10%时，其在低应变率和中应变率下的吸能特性十分接近；当结构应变大于10%时，其在中应变率下的吸能特性略高于低应变率加载时。在不同高应变率(378~1639 s-1)加载条件下，该AlSi10Mg多孔结构吸能特性十分接近。

Additive manufacturing technology has greatly increased opportunities in the production of high-strength aluminum alloy complex parts. However, current additive manufactured aluminum alloy systems are still limited to castable and weldable Al-Si alloys. This impedes the development of high-performance additive manufactured aluminum alloys. Recently, various computational techniques at different scales have been gradually used to promote the development of high-performance additive manufactured aluminum alloys. This paper summarizes the research achievements in the field of computationally-assisted design of additive manufactured aluminum alloys and their preparation from domestic and foreign scholars and presents representative cases from atomic, mesoscopic, and macroscopic scales and machine learning. The different calculation methods used to assist alloy designs are analyzed and their shortcomings are presented. Finally, the prospect on how to improve the application of multi-scale computation techniques in the development of high-performance additive manufactured aluminum alloys is presented, and some specific development directions are also clarified.

增材制造技术为高强铝合金复杂零部件的制造带来了前所未有的机遇，但目前增材制造铝合金体系仍局限于可铸造和可焊接的Al-Si系合金，制约了高性能增材制造铝合金的快速发展。近年来，不同尺度的计算方法逐步用于辅助高性能增材制造铝合金的开发。本文详细综述了国内外学者在计算辅助增材制造铝合金设计与制备领域的研究成果，列举了原子、介观和宏观尺度计算模拟及机器学习等计算方法辅助增材制造铝合金设计的代表性案例，分析了不同计算方法辅助合金设计的策略，并指出其不足。最后，针对如何推动多尺度计算在高性能增材制造铝合金开发中的应用进行了展望，并指出其发展方向。

采用气雾化制粉技术原位合金化制备了AlSi10Mg-Er-Zr粉末,研究了选区激光熔化(SLM)成形AlSi10Mg-Er-Zr试样的相对密度、微观组织和力学性能。结果表明,SLM成形AlSi10Mg-Er-Zr试样的相对密度为99.20%,显微硬度为156.5 HV,室温抗拉强度达到461 MPa,屈服强度为304 MPa,相对于常规AlSi10Mg试样显微硬度提升了25.8%,抗拉强度和屈服强度分别提高了22.6%和26.7%。这是由于Er、Zr元素的加入,细化了SLM成形AlSi10Mg-Er-Zr试样的晶粒尺寸,并且使α-Al基体中Si元素的固溶度增加,由细晶强化和固溶强化机制共同作用提高了AlSi10Mg-Er-Zr合金的力学性能。

The coarsening behavior of Al3Zr precipitates during aging was investigated for two Al-Mg-Zr alloys (Al-3.6Mg-1.2Zr and Al-2.9Mg-2.1Zr, wt%) processed by selective laser melting (SLM). Scanning transmission electron microscopy (STEM) investigations of peak-aged (400 degrees C, 8 h) samples reveal both continuous (similar to 2 nm in diameter) and discontinuous (similar to 5 nm wide and hundreds of nanometers in length) coherent, secondary L1(2)-Al3Zr precipitates. In-situ STEM experiments showed that aging at 400 degrees C results in the appearance and growth of both grain-boundary Al3Zr precipitates, and intragranular nanometer-sized spherical Al3Zr precipitates in Zr-rich dendritic arms. Heating to 500 degrees C resulted in the disappearance of most Al3Zr precipitates and oxide particles. This microstructural evolution sheds light on the evolution of the alloy strength at elevated temperature. For short-term yield tests, as-fabricated samples displayed higher yield strengths than peak-aged samples at temperatures above 150 degrees C (e.g., 87 vs 24 MPa at 260 degrees C). This is attributed to coarsening of grain-boundary precipitates during aging, decreasing their ability to inhibit grain-boundary sliding (GBS) of the fine equiaxed grains (similar to 1 mu m). For longer term creep tests at 260 degrees C, both asfabricated and peak-aged samples displayed near-identical creep behavior during a long-duration (168 h) creep test; by contrast, during a shorter duration creep test (8 h), as-fabricated samples are more creep-resistant than samples previously aged at 260 degrees C (threshold stresses of similar to 40 vs. similar to 14 MPa, respectively). Again, the creep behavior is consistent with coarsening of grain-boundary precipitates, occurring now during long-duration creep tests at 260 degrees C. An exact creep mechanism could not be isolated due to microstructural changes during testing but is believed to be a combination of GBS and dislocation motion. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd.

The AlSi7Mg alloy was fabricated by selective laser melting (SLM), and its microstructure and properties at different building directions after heat treatment were analyzed. Results show that the microstructure of SLM AlSi7Mg samples containes three zones:fine grain zone, coarse grain zone, and heat affected zone. The fine-grain regions locate inside the molten pool, and the grains are equiaxed. The coarse-grain regions locate in the overlap of molten pools. After T6 treatment, the microstructure at the molten pool boundary is still the network eutectic Si, but the network structure becomes discrete, and is composed of intermittent, chain-like eutectic Si particles. The yield strength at three directions (xy, 45°, z direction) of the AlSi7Mg alloy samples fabricated by SLM is improved after T6 heat treatment. The fracture mechanism of the samples is a mixed ductile and brittle fracture before heat treatment and ductile fracture after heat treatment.

<p>Tensile properties and deformation behavior of DP780 steel were studied using servo-hydraulic high-speed material testing machine, SEM and TEM. The effects of strain rate and the mechanism were investigated. The results showed that the strength and ductility of DP780 steel remained almost unchanged as the strain rate increased at strain rates lower than 100 s-1. When the strain rate was over 101 s-1, the strength and the strain-hardening coefficient increased remarkably. Ductility of DP780 steel increased significantly at the strain rates ranging from 3~101&nbsp;to 5~102 s-1. The deformation resistance increased with increasing the strain rate due to the stronger short range resistance induced by the acceleration of dislocation motion in the ferrite matrix. Increasing strain rate up to 3~101 s-1 resulted in a considerable increase of the amount of mobile dislocation, which was the main reason for the increasing uniform elongation and fracture elongation of DP780 steel at the strain rate ranging from 3~101&nbsp;to 5~102 s-1. Interface of ferrite-martensite in DP780 steel was the main location for pile-up of dislocation, crack initiation and propagation. The ability of inhomogeneous plastic deformation of DP780 steel increased due to the decreasing plastic strain energy difference between the ferrite matrix and ferrite-martensite interface and the consequent delaying initiation and propagation of microvoids at ferrite-martensite interface induced by the increasing work hardening degree of ferrite matrix with the increasing strain rate.</p>

利用电液伺服高速试验机对DP780钢进行不同应变速率下的拉伸变形, 结合SEM和TEM等手段, 研究了应变速率对DP780钢拉伸性能及变形行为的影响规律及机制. 结果表明, 在较低应变速率(0 s-1)条件下, 随应变速率增加, DP780钢的强度、塑性等力学性能均未见显著变化. 当应变速率超过101 s-1后, DP780钢的强度和应变硬化指数n明显提高; 塑性在3~101-5~102 s-1范围内出现大幅度增加的现象. 高应变速率的变形过程中, 铁素体基体中位错运动速度加快, 导致&ldquo;近程阻力&rdquo;增大, 使DP780钢的变形抗力随应变速率的增加而增大.在应变速率达到3~101 s-1之后, 铁素体中可动位错数量的大幅度提高, 是DP780钢均匀伸长率和断后伸长率在3~101-5~102 s-1范围内得以明显增加的主要原因. DP780钢中的铁素体/马氏体界面是塑性变形过程中位错塞积、微裂纹形核及扩展的主要位置, 而随应变速率的增加, 铁素体基体中的形变强化程度增大, 可降低铁素体基体与铁素体/马氏体界面之间塑性应变能差异, 延缓铁素体/马氏体界面处微裂纹的形成和扩展, 一定程度上提高了DP780钢非均匀塑性变形能力.

采用光学显微镜和蠕变实验机研究Mg-9Gd-4Y-1Zn-0.5Zr合金在不同温度和应力下的高温蠕变行为。结果表明：在应力为70~130 MPa范围内，200℃时Mg-9Gd-4Y-1Zn-0.5Zr合金的蠕变应力指数n=1.63，蠕变机制为晶界滑动，250℃时蠕变应力指数n=2.63，蠕变机制为位错滑移；在蠕变温度为200~250℃范围内，应力分别为70、90、110和130 MPa时，合金的蠕变激活能Qc分别为108.5、118.9、127.6和134.3 kJ/mol；随着温度和应力的增加，合金晶粒长大，合金的蠕变机制由晶界滑动控制转变为位错滑移控制。