Lattice preferred orientation and stress in polycrystalline hcp-Co plastically deformed under high pressure

The results of x-ray diffraction data of a polycrystal under nonhydrostatic compression are analyzed for lattice preferred orientation and stress using lattice strain theories with an application to hcp-Co deformed up to 42.6GPa in the diamond anvil cell. We obtain a pure [001] fiber texture that develops primarily between 0 and 15GPa. We also show that for hcp metals the hypothesis of uniform stress across grains and lattice planes cannot be applied. This implies that the effective single crystal elastic moduli deduced from x-ray diffraction under Reuss or geometric averages consistently differ from those measured with other techniques, even after including effects of lattice preferred orientations. These results can be interpreted as an (hkl)-dependent effective differential stress resulting from plastic deformation.

利用晶格应变理论，对非静水压压缩下多晶体的X射线衍射数据结果进行了晶格择优取向和应力分析，并应用于在金刚石对顶砧中受压至42.6GPa的六方密堆积（hcp）钴。我们得到了一种主要在0到15GPa之间形成的纯[001]纤维织构。我们还表明，对于hcp金属，不能应用晶粒和晶面间应力均匀的假设。这意味着从X射线衍射根据赖斯（Reuss）平均或几何平均推导出的有效单晶弹性模量，即使在考虑晶格择优取向的影响后，也始终与用其他技术测量的结果不同。这些结果可解释为由塑性变形导致的与（hkl）相关的有效差应力。