材料科学
纳米压痕
位错
准静态过程
应变率
复合材料
变形(气象学)
微观结构
变形机理
恢复系数
喷丸
冶金
机械
热力学
残余应力
物理
作者
Jizhe Cai,Claire Griesbach,Savannah G. Ahnen,Ramathasan Thevamaran
出处
期刊:Acta Materialia
[Elsevier]
日期:2023-05-01
卷期号:249: 118807-118807
被引量:13
标识
DOI:10.1016/j.actamat.2023.118807
摘要
A clear understanding of the dynamic behavior of metals is critical for developing superior structural materials as well as for improving material processing techniques such as cold spray and shot peening. Using a high-velocity (from ∼120 m/s to 700 m/s; strain rates >107 1/s) micro-projectile impact testing and quasistatic (strain rates: 10−2 1/s) nanoindentation, we investigate the strain-rate-dependent mechanical behavior of single-crystal aluminum substrates with (001), (011), and (111) crystal orientations. For all three crystal orientations, the dynamic hardness initially increases with increasing impact velocity and reaches a plateau regime at hardness 5 times higher than that of at quasistatic indentations. Based on coefficient of restitution and post-mortem transmission Kikuchi diffraction analyses, we show that distinct plastic deformation mechanisms with a gradient dislocation density evolution govern the dynamic behavior. We also discover a distinct deformation regime—stable plastic regime—that emerges beyond the deeply plastic regime with unique strain rate insensitive microstructure evolution and dynamic hardness. Our work additionally demonstrates an effective approach to introduce strong spatial gradients in dislocation density in metals by high-velocity projectile impacts to enhance surface mechanical properties, as it can be employed in material processing techniques such as shot peening and surface mechanical attrition treatment.
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