本项目以具有独特负热膨胀行为的富Ti含量Ti-Ni合金为研究对象，采用实验表征与理论分析方法研究合金的马氏体孪晶变体自协作效应和热膨胀响应规律，建立温度变化时合金形状应变与晶体固有膨胀、点阵结构转变和孪晶变体自协作等因素间量化的物理模型，揭示其负热膨胀微观机理及与马氏体相变的本质关系；研究物相组成和微观组织变化等对合金马氏体相变及热膨胀行为的影响规律，阐明合金负热膨胀行为与马氏体相变的关联规律，获得能有效调控合金热膨胀系数的材料设计依据和制备工艺；研究合金马氏体相变过程的等/变温特征属性，掌握合金在经历不同温度时效及热循环条件下其负热膨胀稳定性与马氏体相变等/变温动力学行为的内在规律。本研究将丰富目前有限的关于Ti-Ni合金负热膨胀行为的认知和基础理论体系，为发展新型的具有负热膨胀性能的金属材料提供理论基础，并为开发具有近零膨胀行为或热膨胀系数可调控的Ti-Ni合金及复合材料提供理论指导。

The present project focuses on the research of Ti-rich Ti-Ni alloys exhibiting unique negative thermal expansion behavior. The self-accommodation effect of martensite twin variants and the characteristics of negative thermal expansion responses of the alloy will be studied in detail, and a physical model will be built to quantitatively clarify the correlation between the macroscopic shape strains and the intrinsic crystal thermal expansions, lattice structure transitions and twin variant self-accommodations, thereby the intrinsic correlativity between the negative thermal expansion mechanism and martensitic phase transformations can be revealed. Further, studies will be performed to identify the effect of phase constituents and microstructure characteristics on martensitic phase transformations, and the negative thermal expansion behavior will be investigated deeply. Through establishing the inherent correlativity between the negative thermal expansion behavior and martensitic phase transformations, alloy design criterion and fabrication techniques featuring effectively control on the coefficient of thermal expansion will be obtained. Moreover, the isothermal and athermal nature of martensitic phase transformations of the alloys will be studied in detail, enabling the inherent law between the stability of negative thermal expansion and isothermal/athermal kinetics of martensitic phase transformations, under different thermal aging and thermal cycling conditions, to be found. It is expected that the present research will enrich the understandings and underlying principles of the negative thermal expansion behavior of Ti-rich Ti-Ni alloys, provide guidance for designing novel metallic materials with negative thermal expansion property, in the meanwhile, offer theoretical support for developing Ti-Ni alloys and composites with near zero thermal expansion behavior and controllable coefficient of thermal expansion.