激光立体成形Ti2A1Nb基合金组织演化

Microstructure Evolution of Ti2AlNb-based Alloy by Laser Solid Forming

摘要:

利用SEM、XRD和TEM研究了激光立体成形（LSF, laser solid forming）Ti2A1Nb基合金的组织演化规律。结果表明：激光立体成形Ti2A1Nb基合金沉积态组织由B2/β0相（ordered-bcc）和O相（orthorhombic）组成。沉积态的相组成及微观结构从成形试样顶部→中部→底部呈现从B2/β0固溶体→B2/β0+O魏氏体→B2/β0固溶体的变化，进而使得激光沉积态Ti2A1Nb基合金中间部位的显微硬度值最大，顶部与底部相当。合金显微硬度随激光功率的增大而增大。

关键词:激光立体成形（LSF）;Ti2AlNb基合金;组织;O相

Abstract:

Microstructure evolution and hardness distribution of as-deposited Ti2A1Nb-based alloy by laser solid forming (LSF) was investigated through SEM, XRD and TEM. The results indicate that the LSFed Ti2A1Nb-based alloy was constituted of B2/β0 phase (ordered-bbc) and O phase (orthorhombic). The as-deposited phase in the bottom and top area of the LSF Ti2A1Nb-based alloy sample is B2 phase (Nb-based solid solution), while the phase in the middle area is O phase Widmanstǎttem. The phase evolution through bottom→middle→top is B2/β0→B2/β0+O→B2/β0. Therefore, the microhardness of the middle area for LSFed as-deposited Ti2AlNb-based alloy is maximum, and that of the top and bottom is similar. The microhardness of the alloys increases with the laser power increasing.

Key words:laser solid forming (LSF); Ti2A1Nb-based alloy; microstructures; O phase