激光立体成形Ti-80%Ni合金显微组织及力学性能

MICROSTRUCTURE AND MECHANICAL PROPERTY OF Ti-80%Ni ALLOY PREPARED BY LASER SOLID FORMING

采用激光立体成形技术制备了Ti-80%Ni(质量分数)合金,研究了工艺参量对显微组织和力学性能的影响.结果表明,激光立体成形Ti-80%Ni合金由η-TiNi_3板条和TiNi(B2)+η共晶构成.随着激光扫描速率的增大,η板条逐渐转变为η板条+(TiNi(B2)+η)共晶,η板条尺寸随着扫描速率的增大而减小;随着激光功率的增大,共晶体积分数逐渐增大,η板条逐渐碎断转变为一定取向的块状组织,功率越大,块状组织越细,形成(TiNi(B2)+η)离异共晶组织+板块间(TiNi(B2)+η)共晶组织.激光扫描速率和激光功率的增大均导致硬脆η板条含量减少,合金的成形性和塑性增加.

Ti-80%Ni alloy was prepared by laser solid forming（LSF） under different processing parameters.The microstructure of the alloy consists ofη-TiNi_3 phase under low scanning rate v and power P.With the increase of scanning rate,TiNi（B2）＋ηeutectic appeared,and with the increase of laser power,ηlaths were broken into bulks and distributed along certain orientation,and（TiNi（B_2）＋η） devoiced eutectic＋inter-lath（TiNi（B2）＋η） eutectic appeared.The higher the power is,the finer theηbulks are.And the enhanced power leads to a growing up of（TiNi（B2）＋η） eutectic volume fraction. The microstructure became much fine with increasing v and P,while the volumn fraction of hard-brittleηlath decreased,as a result,the laser formability and plasticity of Ti-80%Ni both increased.