Strong crystal size effect on deformation twinning
Strong crystal size effect on deformation twinning
复制标题
对变形孪晶的强晶体尺寸效应
DOI：
10.1038/nature08692
复制
发表时间：
2010-01-21
期刊：
影响因子：
64.8
通讯作者：
Ma, Evan
中科院分区：
文献类型：
--
作者：
Yu, Qian;Shan, Zhi-Wei;Ma, Evan
晶体中的形变孪晶是一种高度共格的非弹性剪切过程，它控制着许多材料的力学行为，但它的起源和时空特征却一直是个谜。通过微压缩和原位纳米压缩实验，我们发现，随着钛合金单晶样品尺寸的减小，形变孪晶所需的应力急剧增加，直到样品尺寸减小到1 μ m时，形变孪晶完全被相关性较小的普通位错塑性所取代。伴随着变形机制的转变，观察到亚微米尺寸柱的最大流动应力在接近钛的理想强度的值处饱和。我们发展了一个“受激滑移”模型来解释强尺寸依赖的变形孪晶。过渡中的样本量相对较大，在实验中易于获得，这使得我们对尺寸依赖性的理解与应用相关。
Deformation twinning,,,,,in crystals is a highly coherent inelastic shearing process that controls the mechanical behaviour of many materials, but its origin and spatio-temporal features are shrouded in mystery. Using micro-compression andin situnano-compression experiments, here we find that the stress required for deformation twinning increases drastically with decreasing sample size of a titanium alloy single crystal,, until the sample size is reduced to one micrometre, below which the deformation twinning is entirely replaced by less correlated, ordinary dislocation plasticity. Accompanying the transition in deformation mechanism, the maximum flow stress of the submicrometre-sized pillars was observed to saturate at a value close to titanium’s ideal strength,. We develop a ‘stimulated slip’ model to explain the strong size dependence of deformation twinning. The sample size in transition is relatively large and easily accessible in experiments, making our understanding of size dependence,,,,,,relevant for applications.