新型轻质超高强NiTi-Al结构材料力学行为及强韧化机制

项目名称： 新型轻质超高强NiTi-Al结构材料力学行为及强韧化机制

项目编号： No.51471012

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 郑立静

作者单位： 北京航空航天大学

项目金额： 85万元

中文摘要： NiTi-Al金属间化合物是有望满足先进航空发动机中温区使用的超高强新型结构材料。申请者前期采用定向凝固和微合金化法获得了拉伸强度超过2000MPa，断裂韧性为35 MPaom^1/2以上的B2型NiTi-Al金属间化合物，其力学特性表现为超线弹性变形及韧性断裂特征，既不同于B2结构NiAl和FeAl的脆性断裂行为，也不同于NiTi形状记忆合金马氏体相变引起的伪弹性行为。TEM表明，NiTi-Al超高强度和韧性断裂与其形变孪晶与位错、析出相及微裂纹萌生均发生了相互作用有关。本项目拟以定向凝固NiTi-Al结构材料为研究对象，阐明其宏观力学行为，确定高强度和高韧性的关键可控因素，明确孪晶形成机理，孪晶与位错、共格析出相、以及微裂纹萌生与扩展之间相互作用机制，建立宏观力学行为和微观形变机制内在联系，揭示NiTi-Al金属间化合物力学行为和强韧化机理，为发展新型轻质高性能超高强结构材料奠定基础。

中文关键词： 金属间化合物；NiTi-Al结构材料；力学行为；强韧化机理；变形孪晶

英文摘要： NiTi - Al intermetallic compound,as a new ultra-high strength structural materials, is expected to meet the requirement of the medium temperature range of advanced aeroengine. Recently, an ultra-high strength B2 structural NiTi-Al intermetallic compound, with tensile strength more than 2000 MPa and fracture toughness more than 35 MPaom^1/2, were obtained by directional solidification and micro alloying method. The mechanical behavior is is characterized by ultra linear elasticity and ductile fracture, which is different from the brittle fracture behavior of the same B2 structure NiAl and FeAl, and also different from the pseudo elasticity behavior caused by martensitic transformation in NiTi shape memory alloy. TEM results show that the ultra-high strength and ductile fracture are associated with the deformation of twins, the interaction between twins and dislocations, precipitation and micro-crack initiation in the non-martensitic transformation type NiTi-Al intermetallic compound. The project will take directional solidified NiTi-Al intermetallic compound as the research object, aiming to study the macro-deformation behavior, to find the key factors determining high strength and high plasticity, and to discover the twin deformation mechanism, clarifying the interaction between twins and dislocations, precipitates, as well as between micro crack initiation and propagation. It is from atomic scale to reveal the mechanical behavior, strengthening and toughening mechanism of NiTi-Al intermetallic compound, for the development of a new light-weight and high-temperature structure material.

英文关键词： Intermetallic compound;NiTi-Al structural material;Mechanical behavior;Strengthening and toughening mechanism;deformation twins