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内在力学性能。继续我们最近在开发将机械研磨的纳米相金属和合金粉末巩固成全密度样品的程序方面取得的进展，这项工作将对基本性能的研究扩展到许多元素和两相材料。为了系统地研究内在的力学响应，纳米相和超细晶金属和合金的制备将特别注意最小化孔隙率和颗粒脱粘问题。测试将在压缩和拉伸中进行。基本的变形行为和机制将被研究。特别是，变形前后、晶粒内部和界面附近（晶粒与相界）的单相和两相合金中的位错结构和行为，将在一系列晶粒尺寸范围内进行表征和监测。研究了复合材料的应变硬化和剪切带行为及其对成分和晶粒尺寸的依赖关系，并与传统材料进行了比较。对多相合金中相界面的强化作用进行了表征和模拟。纳米晶金属和多相合金具有有用的机械性能组合将被展示

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.***