Mechanical/thermal responses and microstructure evolution of ultrafine - (UF) and nano-grained materials with high density UF/nano-sized growth twins

具有高密度UF/纳米尺寸生长孪晶的超细（UF）和纳米晶材料的机械/热响应和微观结构演化

• 批准号: 46427-2009
• 负责人: Wang, Zhirui
• 金额: $ 1.68万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=451082
• 关键词: Mechanical; thermal; responses; microstructure; evolution

Ultrafine-(UF) and nano-grained materials have attracted much interest of researchers in the field of materials science and engineering due to their superior properties over the traditional counterparts. However, the microstructures in these materials are generally thermodynamically unstable, with a strong tendency to transform into normal polycrystals with coarser grain size, leading to the loss of their improved or novel properties. Therefore, microstructural responses and evolution in UF/Nano-materials upon thermal and mechanical activations are of great interest for both practical and scientific reasons, as well documented in numerous publications. In recent years, many newly developed techniques for processing UF/Nano-materials introduce a large amount of UF/Nano growth-twins in these materials, such as Cu, Ni and austenite steels. These twins are usually very small with submicro- and nano-meter width, and they induce many special mechanical phenomena such as strong strengthening effect. However, these twins are found with low stability, i.e. they may recede, disappear and even convert to dislocation structures upon annealing and/or plastic deformation. Up to the present, no systematic investigations have been reported that detail these phenomena as well as related mechanisms. In fact, many aspects of these growth twins have still remained ambiguous. The present work will tackle these issues with the objective to understand the fundamental aspects of the above phenomena. Special attention will be paid to the dislocation - twin conversion mechanism.

由于其优越的特性超过了传统的对应物，因此超铁（UF）和纳米颗粒材料在材料科学和工程领域引起了研究人员的极大兴趣。但是，这些材料中的微观结构通常在热力学上不稳定，其强烈的趋势是转化为具有更粗的晶粒尺寸的正常多晶体，从而导致其改善或新颖的特性丧失。因此，由于实用和科学原因，在热和机械激活时在UF/纳米材料中的微观结构反应和演变引起了人们的极大兴趣，并且在许多出版物中都记录在许多出版物中。近年来，许多新开发的用于处理UF/纳米材料的技术在这些材料中引入了大量的UF/纳米生长双线，例如Cu，Ni和Austenite Steels。这些双胞胎通常很小，具有亚微米和纳米米宽度，它们会诱导许多特殊的机械现象，例如强大的增强作用。但是，这些双胞胎的稳定性低，即它们可能会消失，甚至转化为脱位结构，后将其退火和/或塑性变形后转化为脱位结构。直到目前，尚无系统的调查，详细介绍了这些现象以及相关机制。实际上，这些增长双胞胎的许多方面仍然模棱两可。目前的工作将解决这些问题，以了解上述现象的基本方面。将特别注意错位 - 双转换机制。