权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Study of microscopic mechanism of plastic deformation in inorganic materials with non-periodic structure

非周期结构无机材料塑性变形微观机理研究

基本信息

批准号：
12450261
负责人：
TAKEUCHI Shin
金额：
$ 9.22万
依托单位：
Tokyo University of Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

It has been clarified that quasicrystals and metallic glasses, both having non-translational symmetry structure, can undergo plastic deformation by slip process. The purpose of the research is to elucidate the microscopic slip deformation mechanisms in these materials of non-translational symmetry, by means of experiments over a wide deformation conditions and of computer simulations(1) As a result of high temperature deformation experiments on various quasicrysmtals, the following facts have been clarified:(a) any quasicrystal can be plastically deformed only above 0.75Tm (Tm: melting point), and the yield stress decreases rapidly with increasing temperature, (b) quasicrystals commonly exhibit pronounced work-softening, and (c) the work-softening is concluded to occur as a result of decreasing activation enthalpy. Based on the computer simulation of dislocations in model quasicrystals, the dislocation glide in a quasicrystal is exerted by a resistance due to a phason wall production s … More uperimposed by that due to a quasiperiodic Peierls potential, and its rate is controlled by kink-pair formation at high temperatures. The deformation behavior is well explained by the model where on the phason-free quasicrystal the dislocation mobility is governed by kink-pair formation at large Peierls potentials, while as phason- defect density increases with plastic deformation it is governed by that at small Peierls potentials(2) Deformation experiments of bulk metallic glasses over a wide temperature range have been shown that their yield stresses are almost temperature independent down to near zero Kelvin. In order to elucidate what kink of dislocation glide governs the slip in metallic glasses, computer simulation studies have been performed. A realistic model binary metallic glass has been constructed by means of the inverse Monte Carlo method and by use of interatomic potentials for a Ni-Nb alloy. It has been classified that dislocation is stable only when its Burgers vector is larger than about 3A. The slip deformation model for the dislocation of the minimum Burgers vector is tentatively assumed, but the final deformation model has not been established yet, since the simulation for the dislocation glide has not been completed Less

准晶和金属玻璃都具有非平移对称结构，它们都可以通过滑移过程发生塑性变形。本研究的目的是通过宽变形条件下的实验和计算机模拟，阐明非平移对称材料的微观滑移变形机制。(1)各种准晶高温变形实验的结果表明：(A)任何准晶都只能在0.75Tm(TM：熔点)以上塑性变形，且屈服应力随温度的升高而迅速下降，(B)准晶通常表现出明显的功软化，以及(C)功软化是激活能降低的结果。基于模型准晶中位错的计算机模拟，准晶中位错的滑移是由相子壁产生的电阻S…引起的由于准周期的Peierls势，其速率受高温下扭结对的形成所控制。该模型很好地解释了形变行为，在无相子准晶上，位错的迁移率由大Peierls势下扭结对的形成所控制，而当相缺陷密度随塑性变形而增加时，它由小Peierls势下的相缺陷密度所控制。(2)大块金属玻璃在宽温度范围内的变形实验表明，它们的屈服应力几乎与温度无关，直到接近零的开尔文。为了阐明金属玻璃的滑移是由哪种位错滑移引起的，进行了计算机模拟研究。用逆蒙特卡罗方法和原子间相互作用势构造了一个真实的二元金属玻璃模型。位错只有在其Burgers矢量大于约3A时才是稳定的。初步假设了位错的滑移变形模型为最小Burgers矢量，但由于位错滑移的模拟尚未完成，最终的变形模型尚未建立