Properties of Consolidated Nanocrystalline Metals and Composites

本研究的主要目的是了解全密度纳米晶金属合金的固有力学性能。继续我们最近在机械球磨纳米金属和合金粉末固化成全密度样品方面的进展，这项工作将基本性质的研究扩展到一些元素和两相材料。为了系统地研究本征机械响应，将特别注意纳米相和超细晶金属和合金的制备，以最大限度地减少气孔和颗粒脱粘问题。测试将在压缩和拉伸状态下进行。将对基本变形行为和机制进行研究。特别是，单相和两相合金在变形前后、晶内和界面附近(晶界与相界)的位错结构和行为将在一定的晶粒度范围内进行表征和监测。将研究应变硬化和剪切带状行为及其与成分和晶粒度的依赖关系，并与传统材料中的结果进行比较。对多相合金中相界的强化作用进行了表征和模拟。将展示具有有用的机械性能组合的纳米晶金属和多相合金。

The main objective of this research is to understand the inherent mechanical properties of full-density nanocrystalline metallic alloys. Continuing on with our recent progress in devloping procedures to consolidate mechanicallu milled nanophase metal and alloy powders into full-density samples, this work expands the investigation on basic properties to a number of elemental and two phase materials. To systematically investigate the intrinsic mechanical response, nanophase and ultrafine-grained metals and alloys will be prepared with special care taken to minimize porosity and particle debonding problems. Testing will be conducted in compression and tension. Fundamental deformation behavior and mechanisms will be studies. In particular, dislocation structure and behavior in single-and two-phase alloys, before and after deformation, inside grains and near interfaces (grain vs. phase boundaries), will be characterized and monitored over a range of grain sizes. The strain hardening and shear banding behavior and their dependence on composition and grain size will be investigated and compared with those found in conventional materials. The strengthening effects of interphase boundaries in multi-phase alloys will be characterized and modeled. Nanocrystalline metals and multi-phase alloys with a useful combination of mechanical properties will be demonstrated.***