Ultrafine grained metals and metal matrix nanocomposites with enhanced strength and good tensile ductility for structural applications have been successfully fabricated by processing and thermomechanically consolidating powders and, in some cases, post-consolidation heat and thermomechanical treatments. This paper provides an overview of the substantial amount of research work mainly published by the author’s research groups rather than a comprehensive review of the vast amount of very active research work published in this area. The microstructures and tensile properties of the samples fabricated and the correlations between them strongly suggest that the synergistic effects of grain boundary strengthening and intragranular ceramic (and other hard) nanoparticles are highly desirable for significantly enhancing the tensile yield strength and maintaining generally good tensile ductility. The extra boundaries between hard regions and soft regions introduced by heterogeneous microstructure can further enhance the strength of the material without sacrificing tensile ductility by inducing back stress in the soft regions. However, these boundaries also induce forward stress in the hard regions which has a weakening effect on them and needs to be managed by dispersing nanoparticles in the hard regions or other means.

通过加工和热机械固结粉末，以及在某些情况下，后固结热处理和热机械处理，已成功制造出用于结构应用的具有增强强度和良好拉伸延展性的超细晶粒金属和金属基体纳米复合材料。本文概述了主要由作者的研究小组发表的大量研究工作，而不是对该领域发表的大量非常活跃的研究工作的全面回顾。制造的样品的微观结构和拉伸性能以及它们之间的相关性强烈表明，晶界强化和粒内陶瓷（和其他硬质）纳米粒子的协同效应对于显着提高拉伸屈服强度和保持总体良好的拉伸延展性非常理想。由异质微观结构引入的硬区和软区之间的额外边界可以通过在软区引入背应力来进一步提高材料的强度，而不会牺牲拉伸延展性。然而，这些边界也会在硬区引起前向应力，这对它们有削弱作用，需要通过将纳米粒子分散在硬区或其他方式来管理。由异质微观结构引入的硬区和软区之间的额外边界可以通过在软区引入背应力来进一步提高材料的强度，而不会牺牲拉伸延展性。然而，这些边界也会在硬区引起前向应力，这对它们有削弱作用，需要通过将纳米粒子分散在硬区或其他方式来管理。由异质微观结构引入的硬区和软区之间的额外边界可以通过在软区引入背应力来进一步提高材料的强度，而不会牺牲拉伸延展性。然而，这些边界也会在硬区引起前向应力，这对它们有削弱作用，需要通过将纳米粒子分散在硬区或其他方式来管理。