Study On The Precision And Performance Control Of Shape Memory Alloy Structural Components By Selective Laser Melting

Ti-Ni alloy is widely used in aerospace,medical,mechanical manufacturing,electronics and transportation fields because of its shape memory effect,superelasticity,high damping,biocompatibility,wear resistance,elastic thermal properties and other properties.It is currently the shape memory alloy with the best memory performance,the widest application range and the most applications.However,due to the high hardness of Ti-Ni alloy,the martensitic transformation process and microstructure are easily affected by machining behavior as well as thermal conditions,and the cutting performance is poor,it is difficult to obtain Ti-Ni alloy workpieces with uniform composition,high precision,excellent performance and complex structure through one-step casting or secondary processing.Therefore,how to rapidly form fine and complex Ti-Ni shape memory alloy devices has become a problem in this field.At present,scholars have combined metal 3D printing technology to carry out research on Ti-Ni alloy additive manufacturing,and the best tensile properties of the material are between 15%～20%.Nevertheless,the research content mostly revolves around the material science or the influence of printing process parameters on the martensite transformation behavior,and there is no report on the mechanical properties of 3D printed Ti-Ni shape memory alloy structural parts.In this paper,a variety of 50.2at%Ni Ti-Ni alloy fine structures are prepared based on laser selective melting technology.Then,the Ti-Ni alloy workpieces will be systematically discussed and studied in depth from the aspects of material properties,structural size differences,mechanical properties,shape memory function,parameter adjustment and so on.In this paper,thin-walled components with negative Poisson’s ratio and spiral lattice components with different process parameters were prepared by laser selective melting technology firstly.Then combined with the experimental results,the method of preparing Ti-Ni alloy components by laser selective melting technology was summarized,and a set of technical parameter package for forming Ti-Ni shape memory alloy components was obtained.The roughness,dimensional accuracy and holes defect types of components with different process parameters were characterized by laser confocal microscope and computer tomography technology.According to the observations of metallographic samples,scanning electron microscopy and transmission electron microscopy,the influence of main process parameters on the morphology accuracy and mechanical properties of Ti-Ni shape memory alloy fine components is revealed,and the internal mechanism of the change in its properties is explained.This paper proposes a preparation method to control,improve and enhance the morphology and performance of Ti-Ni fine components.Quasi-static compression experiments and shape memory effect tests were carried out on components with different process parameters,and the changes in mechanical properties and phase transition behaviors were analyzed.It is hoped that the research in this paper will provide some technical references for Ti-Ni shape memory alloy components used in different fields in terms of shape design,performance indicators,and process parameters.