Local microstructure evolution and mechanical performance of friction stir additive manufactured 2195 Al-Li alloy
Local microstructure evolution and mechanical performance of friction stir additive manufactured 2195 Al-Li alloy
复制标题
DOI：
10.1016/j.matchar.2022.111818
复制
发表时间：
2022-04
影响因子：
4.7
通讯作者：
Z. Shen;S. Chen;L. Cui;D. Li;X. Liu;W. Hou;H. Chen;Z. Sun;W.Y. Li
中科院分区：
文献类型：
--
作者：
Z. Shen;S. Chen;L. Cui;D. Li;X. Liu;W. Hou;H. Chen;Z. Sun;W.Y. Li
本文主要从搅拌摩擦添加剂制造（FSAM） 2195铝锂合金的局部组织演变和力学性能两方面进行了研究。利用光学显微镜（OM）、电子背散射衍射（EBSD）和透射电镜（TEM）技术表征了局部微观结构，并通过显微硬度和拉伸测试对其力学性能进行了评价。结果表明：采用多道次FSAM工艺制备了2195铝锂合金的多层叠层；在熔核区（NZ）观察到细小的等轴晶粒，但未发现空洞或亲和键等缺陷。沿NZ深度的平均晶粒尺寸减小和低角度边界（LABs）归因于旋转刀具的反复搅拌作用。降水相的分布主要由热循环决定。基材（BM）中存在大量的t1和θ′相，有利于提高材料的硬度和强度。这些析出物在NZ和热机械影响区（TMAZ）溶解，在热影响区（HAZ）变粗，造成硬度和强度损失。同样，在建造方向上，沉淀物的形态、大小和分布也不同。优异的抗拉强度和伸长率被确定在NZ，这是由于细晶粒和理想的沉淀表征。
The present investigation is mainly focused on friction stir additive manufactured (FSAM) 2195 Al-Li alloy in aspects of localized microstructure evolution and mechanical performance. Characterization of the localized microstructure was conducted by optical microscope (OM), electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM) techniques, and mechanical properties were evaluated based on micro-hardness and tensile testing measurements. Results showed a build of multilayered stack of 2195 aluminum lithium alloy was fabricated using FSAM via multi-pass processing. Defects such as voids or kissing bond were not identified, and fine equiaxed grains were observed in the nugget zone (NZ). The decrease of average grain size and low angle boundaries (LABs) along the depth of the NZ was attributed to repetitive stirring action of the rotating tool. Distribution of precipitation phase is mainly determined by the thermal cycle. Numerous T1andθ′ precipitates were identified in the base material (BM), which are beneficial to improve material hardness and thus strength. These precipitates were dissolved in NZ and thermo-mechanically affected zone (TMAZ), and coarsen in heat affected zone (HAZ), which caused loss of hardness and strength. Similarly, precipitate morphology, size, and distribution are different in the built direction. Excellent tensile strength and elongation were identified in the NZ, which is attributed to fine grains and desirable precipitate characterization.