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Nanostructure control

纳米结构控制

基本信息

批准号：
08242106
负责人：
MAKI Tadashi
金额：
$ 46.21万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

The purpose of the present research project is to establish various methods of nanostructure control and to make clear the mechanism of superplasticity in various materials such as metals and alloys, intermetallics and ceramics. The main results obtained are as follows.(1) New types of heat treatments for appearance of superplasticity in duplex stainless steel and high carbon steel were developed. Microduplex structure with a grain size of 0.5〜1.0μm can be obtained by simple treatments such as heavy cold-rolling of as-received hot-rolled plates in duplex stainless steel and the quenching from (γ + θ) temperature in high carbon steel.(2) Effect of liquid phase at grain boundaries on superplasticity was investigated in particle-dispersed aluminum alloys. A large elongation was obtained at temperatures just below the solidus one for a 7475 Al alloy. The thickness of liquid phase in the test condition corresponding to the peak elongation was estimated to be 10〜60nm for the 7475 alloy.(3) Mechanism of superplastic deformation in monolithic intermetallics was found to depend on ordered crystal structure. Grain boundary sliding plays an important role in fcc-derivative intermetallics exhibiting fine-grained superplasticity, while dynamic recrystallization and/or dynamic recovery is responsible for coarse-grained superplasticity in bcc-derivative intermetallics.(4) The effect of Mg, Ca, Sr and Ba additions on the grain size refinement of Y-TZP and Ce-TZP was studied. It was found that Ca is the most effective element for the grain refinement. The addition of small amount of CuO in Y-TZP was found to be effective in reducing the sintering temperature, grain size and the stress rcquired for superplastic deformation.

本研究项目的目的是建立各种纳米结构控制的方法，并阐明金属和合金、金属间化合物和陶瓷等各种材料的超塑性机理。主要研究结果如下：(1)针对双相不锈钢和高碳钢的超塑性现象，开发了新型热处理工艺。双相不锈钢热轧板材经大冷轧、高碳钢经(μ)温度淬火等简单处理可获得晶粒度为0.5~1.0γ+θm的微观双相组织。(2)研究了颗粒弥散铝合金中晶界液态相对超塑性的影响。在低于固相线的温度下，7475铝合金获得了较大的延伸率。实验条件下7475合金的峰值延伸率对应的液态相厚度为10~60 nm。(3)金属间化合物的超塑性变形机制与有序晶体结构有关。晶界滑移对面心立方衍生金属间化合物的细晶超塑性起重要作用，而动态再结晶和/或动态回复是体心立方衍生金属间化合物粗晶超塑性的主要原因。(4)研究了添加镁、钙、锶、钡对Y-TZP和Ce-TZP的细化作用。结果表明，Ca是细化晶粒的最有效元素。在Y-TZP中加入少量CuO能有效地降低超塑性变形所需的烧结温度、晶粒度和应力。