SLM NiTi记忆合金bcc点阵结构的吸能特性研究  

Energy Absorption Characteristics Study of SLM NiTi bcc Lattice Structure

作　　者：向政 陈捷 杨琴 沈显峰[1] 霍明政 袁上钦 戴东华 黄姝珂[1] Xiang Zheng;Chen Jie;Yang Qin;Shen Xianfeng;Huo Mingzheng;Yuan Shangqin;Dai Donghua;Huang Shuke(Institute of Machinery Manufacturing Technology,CAEP,Mianyang 621900,China;Northwestern Polytechnical University,Xi’an 710072,China;Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]中国工程物理研究院机械制造工艺研究所,四川绵阳621900 [2]西北工业大学,陕西西安710072 [3]南京航空航天大学,江苏南京210016

出　　处：《稀有金属材料与工程》2022年第11期4279-4288,共10页Rare Metal Materials and Engineering

基　　金：国家自然科学基金委员会-中国工程物理研究院NSAF联合基金(U1930207);青年科学基金(52001289)。

摘　　要：通过选区激光熔化(SLM)技术制备了不同体积分数的NiTi记忆合金bcc点阵结构(基于CAD及基于三周期极小曲面TPMS),分析了失效前的压缩响应,研究了体积分数、单元构型和微观组织对能量吸收的影响。结果表明:NiTi bcc点阵(体积分数5%~25%)在压缩至损伤前具有优秀的比能量吸收(0.45~1.89 J/g),卸载后加热可恢复至92%以上;体积分数及单元构型对NiTi bcc点阵的压缩响应有重要影响;体积分数小于15%时,CAD样品具有更长可压缩应变,比能量吸收更好;体积分数大于15%时,TPMS样品具有更高压缩应力,比能量吸收更好;SLM过程中的阶梯效应导致了点阵支杆的下表面与内部具有不同的材料组织,下表面处熔池条纹更深更宽且晶粒更加粗大;材料异质性导致了相对较差的机械性能,不利于能量吸收;由于受载下应力集中位置及异质比例的不同,该材料异质性对低体积分数的TPMS样品的不利影响更大。In this study,the bcc lattice structure(CAD-based and TPMS-based)of NiTi memory alloy with different volume fractions were fabricated by selective laser melting(SLM).The compression response before failure was analyzed.The effects of volume fraction,unit configuration and microstructure on energy absorption were studied.The results show that the NiTi bcc structure(volume fraction 5%~25%)has excellent specific energy absorption(0.45~1.89 J/g)before compressing to damage,and can recover to more than 92%of the initial height after heating.Volume fraction and unit configuration have an important influence on the compression response of NiTi alloy bcc lattice structure.When the volume fraction is less than 15%,the traditional CAD sample has longer compressible strain and better specific energy absorption than the TPMS sample.When the volume fraction is greater than 15%,the TPMS sample has higher compressive stress and better specific energy absorption than the CAD sample.The ladder effect in the SLM process leads to different material microstructures on the lower surface and inside of the lattice structure,the molten pool streaks at the lower surface is deeper and wider,and the grains are larger.The heterogeneity of the material leads to relatively poor mechanical properties,which is not conducive to energy absorption.Due to the different stress concentration locations and heterogeneous ratios,material heterogeneity has a greater adverse effect on low volume fraction TPMS samples.

关 键 词：NITI形状记忆合金 点阵结构 选区激光熔化 比能量吸收 

分 类 号：TG139.6[一般工业技术—材料科学与工程]