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Development of toughened metal/intermetallic layered materials

增韧金属/金属间化合物层状材料的开发

基本信息

批准号：
11450261
负责人：
ENOKI Manabu
金额：
$ 8.9万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Materials are recently requested to have various functions. Intermetallics which have excellent strength and oxidation resistance are expected as high temperature structural materials. However, their application in monolithic form is very limited because of their lack of ductility and brittleness. Layered materials with ductile metals and brittle intermetallics are expected to have novel properties, especially enhancement of fracture resistance in specific direction. One of the methods to fabricate these metals/intermetallics layered materials is a self-propagated high temperature synthesis, and we have investigated Ni/Ni-Al, Ti/Ti-Al and Nb/Nb-Al layered materials. However, microvoids which are produced in intermetallic layer during hot-press processing affect the fracture behavior and reduce the strength of materials. In the present research we have tried the fabrication of layered materials with fewer microvoids by thin metal sheets processing and the change of intermetallic phase by different processing conditions of heat temperature and pressure. Also the mechanical properties and fracture mechanism of layered materials were investigated as well as the processing for excellent layered materials. Layered materials of Ni/Ni-Al with different thickness of metal layer and different intermetallic phase were successfully fabricated by self-propagating high temperature synthesis using hot-press from thin metal sheets of Ni and Al. The change of intermetallic phase gave the increase of both tensile strength and elongation. Crack propagation behavior in these materials was evaluated, and the criterion for crack direction whether a crack propagates straightly or deflects laterally was proposed using the analysis of stress field around crack tip.

最近要求材料具有各种功能。金属间化合物具有优异的强度和抗氧化性，有望成为高温结构材料。然而，由于其缺乏延性和脆性，其整体形式的应用非常有限。具有延性金属和脆性金属间化合物的层状材料有望具有新的性能，特别是在特定方向上增强抗断裂性能。自蔓延高温合成是制备这些金属/金属间化合物层状材料的方法之一，我们研究了Ni/Ni-Al、Ti/Ti-Al和Nb/Nb-Al层状材料。然而，在热压过程中，金属间化合物层中会产生微孔洞，影响材料的断裂行为，降低材料的强度。在本研究中，我们尝试了通过金属薄板加工来制备微孔洞较少的层状材料，并通过不同的加热、温度和压力的加工条件来改变金属间化合物相。研究了层状材料的力学性能和断裂机理，以及制备性能优良的层状材料的工艺。采用自蔓延高温合成技术，以Ni、Al薄板为原料，采用自蔓延高温合成技术，成功地制备了不同金属层厚度、不同金属间化合物相组成的Ni/Ni-Al层状材料。金属间化合物相的变化使合金的抗拉强度和延伸率均有所提高。通过对裂纹尖端应力场的分析，评价了裂纹在这些材料中的扩展行为，并提出了裂纹是直线扩展还是横向偏转的裂纹方向判据。