混合元素法激光立体成形Ti-XAl-YV合金的微观组织演化

研究了混合元素法激光多层沉积Ti-XAl-YV(X≤11,Y≤10)(质量分数,%,下同)合金的微观组织随Al、V元素含量的演化规律。结果发现:随Al、V含量的增加,Ti-XAl-YV合金原始β晶内α域的尺寸和数量逐渐减小,原始β晶内的显微组织逐渐由魏氏组织转化为α和β编织细密的网篮组织,且α板条的尺寸和长宽比显著减小。结合单道多层激光沉积过程热历史循环曲线的计算、合金相变点温度的计算以及Ti-XAl-YV合金的相图分析,研究了单道多层激光沉积Ti-XAl-YV合金α相的形核和生长条件,揭示了微观相结构演化机理。

Microstructure Evolution of Laser Solid Formed Ti-XAl-YV Alloys from Blended Elemental Powders

The microstructure evolution of laser multi-layer deposited Ti-XAl-YV (X≤11,Y≤10,mass fraction,%,similarly hereinafter) alloys from blended elemental powders with the content of Al and V was studied.Results show that the size and quantity of α colony in the prior β grains are decreased gradually with the increase of Al and V,and the microstructure in prior β grains changes from widmansttten structure to basketweave structure with the α laths and β phase braided.Meanwhile,the size and aspect ratio of α laths are decreased obviously.The nucleation and growth conditions of α phase in single-line laser multi-layer deposited Ti-XAl-YV alloys were analyzed and the microstructure evolution mechanism was revealed on the basis of thermal history modeling,α→β transformation temperature computation and the phase diagram analysis of Ti-XAl-YV alloys.