混合元素法激光立体成形Ti-XAl-YV合金的微观组织演化

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

摘要:

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b晶内a域的尺寸和数量逐渐减小，原始b晶内的显微组织逐渐由魏氏组织转化为a和b编织细密的网篮组织，且a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a相的形核和生长条件，揭示了微观相结构演化机理。

Abstract:

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 a colony in the prior b grains are decreased gradually with the increase of Al and V, and the microstructure in prior b grains changes from widmanst?tten structure to basketweave structure with the a laths and b phase braided. Meanwhile, the size and aspect ratio of a laths are decreased obviously. The nucleation and growth conditions of a 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, a→b transformation temperature computation and the phase diagram analysis of Ti-XAl-YV alloys.