为了满足不同领域对材料热膨胀性能的需求，一般通过复合材料或者成分调整等手段来实现对材料热膨胀行为的调控。本申请项目基于渐进式应变玻璃相变及其合金微结构的不均匀性，提出一种通过外加应力来调控材料热膨胀行为的新思路：即通过应力控制应变玻璃相变过程中纳米应变畴的数量和尺寸，进而减小、抵消、甚至逆转基体的正热膨胀行为，使得同一个材料在不同的应力作用下能呈现正热膨胀，零热膨胀，甚至负热膨胀。本项目拟首先从实验上探明应力调控热膨胀行为的可行性，普遍性和规律性；进而通过理论模拟与实验相结合的方式揭示其内在物理机制。本项目的工作可望为实现人为实时精确调控材料的热膨胀行为提供原理性基础；同时关于玻璃态材料微结构及其新功能性的探索也具有重要的理论研究价值。

Most materials expand or contract with increase or decrease in temperature; this effect is known as the normal "thermal expansion" behavior. In order to control the thermal expansion behavior of materials, two common approaches are widely used. One is combining materials with different thermal expansion behavior. However, this method may leads to local stresses and strains that often enhance materials fatigue and thus shorten the component lifetime. The other is altering the composition or thermal treatment of some special single, uncombined materials, which has attracted much attention in recent years... Different from the above two methods, in this proposal, the applicant intends to propose a new way, i.e., tune the thermal expansion behavior of a strain glass alloy by external stress. This idea is based on the strain glass transition and the heterogeneity of micro-structures in strain glass alloys. During strain glass transition on cooling, one portion of the high temperature phase transforms into nanodomains with larger volume; this transformation causes volume expansion. The remaining portion of the high temperature phase keeps unchanged and undergoes normal volume contraction. Thus, these two opposite effects will compensate each other to some extent. Furthermore, previous studies indicate that applying external stress will promote the population of these nanodomains. Therefore, by altering external stress, the proportion of the above two opposite effects will be changed, and consequently the thermal expansion behavior of the whole alloy can be adjusted. With increasing external stress, the thermal expansion coefficient is expected to vary linearly from positive through zero then to negative. .. This study will involve both experiment and computer simulation to achieve the final goal. On one hand, experimentally the applicant intends to prove the feasibility of tuning thermal expansion behavior by external stress in strain glass alloys, then to check whether such effect is universal by studying different strain glass systems and finally obtain the relationship between thermal expansion coefficient and external stress. On the other hand, with the help of Landau-Ginzburg simulation, the underlying mechanism of such effect is expected to be clarified, by probing the dynamic evolution of nanodomains under different external stress on cooling. This study can offer a new idea to control the thermal expansion behavior of a material precisely and also provide important implications in understanding the properties and structure of glassy materials.