激光立体成形Ti-20%Ni合金枝晶的组织演化

DENDRITE STRUCTURE EVOLUTION IN Ti-20%Ni ALLOY PREPARED BY LASER SOLID FORMING

Ti-20%Ni(质量分数)合金激光立体成形组织由β-Ti枝晶和枝晶间(β-Ti+Ti_2Ni)层片共晶及棒状共晶组成.随着激光能量密度D_e减小,枝晶特征尺寸F减小.枝晶特征尺寸及共晶间距的变化规律分别与枝品生长KGT经典模型和共晶生长TMK经典模型吻合较好.

The microstructure of Ti 20%Ni alloy （mass fraction） prepared by laser solid forming consists of β-Ti dendrite and （β-Ti＋Ti2Ni） lamellar eutectic plus a little amount of rod like eutectics between dendrites. The characteristic dendritic size F decreased with decreasing laser energy density De. On the other hand, the eutectic spacing also decreased with the increase of scanning velocity. The variations of the characteristic dendritic size and eutectic spacing are roughly in accord with the KGT （Kurz-Giovanola-Trivedi） model and TMK （Trivedi-Magnin Kurz） model, respectively.