细晶Zr-Cu-Ni-Co合金薄带马氏体相变的尺寸效应与高温形状记忆特性

ZrCu alloy has advantages of low price and controllable martensitic transformation temperature from 25 to 1050℃, which make it considered as a promising high temperature shape memory alloys candidate. The applicant's previous studies have found that Ni and Co co-doping increased martensitic transformation temperature, decreased thermal hysteresis and improved thermal stability, but its plasticity is poor and the shape memory effect still need to be improved. Due to the fact that ZrCu alloy has a high amorphous formation ability, the amorphous Zr-Cu-Ni-Co ribbons will be easily fabricated using melt-spinning method in the present project. Nanoscale Zr-Cu-Ni-Co ribbons with a combination of good plasticity, toughness as well as strain recovery characteristics can be obtained during the proper crystallization process. The influence of grain size on the microstructure, martensitic transformation behavior, mechanical properties and shape memory effect is investigated. The corresponding optimum grain size of high martensitic transformation temperature, high thermal stability and large reversible strain is determined. The microstructure evolution laws of martensite during deformation is clarified in the amorphous Zr-Cu-Ni-Co ribbons and the micro-mechanism of large reversible strain is also disclosed. The inherent relationship among grain size, martensitic transformation behavior and reversible strain is established. These studies will lay the foundation of fabricating new Zr-Cu-Ni-Co high temperature shape memory alloys with a combination of plasticity, toughness and strain recovery.

ZrCu合金价格低廉，相变温度在25-1050℃较大温度区间内可调，是一种极具应用潜力的高温形状记忆合金。申请者前期研究发现，Ni、Co掺杂后相变温度提高，热滞减小，热稳定性改善，但其塑性差，形状记忆效应有待提高。因ZrCu非晶形成能力超强，本项目拟采用甩带法制备Zr-Cu-Ni-Co非晶薄带，通过合适的晶化处理工艺得到兼具良好塑韧性和应变恢复特性的纳米晶Zr-Cu-Ni-Co薄带。研究晶粒尺寸对微观组织结构、马氏体相变行为、力学行为和形状记忆效应的尺寸效应，确定具有高相变温度、高热稳定性和大可逆应变的最佳晶粒尺寸；阐明纳米晶Zr-Cu-Ni-Co薄带中马氏体在变形过程中微观组织结构演化规律，揭示获得大的可恢复应变的微观机制；建立晶粒尺寸、马氏体相变、可逆应变之间的内在联系，为制备出良好塑性及应变恢复特性的新型Zr-Cu-Ni-Co高温记忆合金奠定基础。

本项目研究了细晶Zr-Cu-Ni-Co合金薄带马氏体相变与力学性能。为解决Zr-Cu基高温形状记忆合金力学性能差，形状记忆效应差这一缺点，采用“非晶+晶化”细化晶粒及引入纳米析出相的方法，在Zr-Cu基高温记忆合金中获得良好的拉伸力学性能。系统研究Zr-Cu基合金薄带中非晶约束状态下和马氏体状态下相变行为、晶化行为、马氏体显微组织及亚结构、马氏体变体间界面结构、以及力学性能等的影响规律和内在本质；揭示纳米析出相在马氏体变形过程中对组织结构、界面结构及其可动性的影响规律和微观机制；揭示含有纳米析出相的Zr-Cu基高温记忆合金薄带呈现良好力学能的物理本质；为具有优异形状记忆效应的高温形状记忆合金的研制和应用奠定理论基础。