变形量对激光立体成形Ti3Al/TC11过渡区显微硬度及合金元素扩散的影响

Effect of deformation amount on the microhardness and element diffusion of the transition zone for Ti3Al/TC11 by laser solid

摘要:

对激光立体成形制备的Ti3Al/TC11双合金件进行了近等温锻造，研究经不同程度变形后过渡区的显微硬度及其合金元素的扩散情况。结果表明：经过近等温锻造后，无论所采用变形量的大小，Ti3Al/TC11过渡区及其两侧的显微硬度值均显著降低，且差异减小分布趋于均匀。变形量对过渡区显微硬度及其合金元素的扩散均有显著影响。随着变形量的增大，沿整个试样的显微硬度值均增大且其分布的均匀性提高；随着变形量的增大，过渡区及与基体交界处的合金元素浓度梯度减小，扩散比较充分。这与随着变形量的增大使得激光成形时所形成的粗大柱状组织被充分破碎，β晶界消失，α相和α2相呈现出细小等轴的组织形态有关。

Abstract:

The Ti3Al/TC11 dual alloy specimen were prepared by laser solid forming, and then deformed by near isothermal forging with various deformation amounts. Afterwards, the effect of deformation amount on the microhardness and element diffusion of the transition zone and its two sides for Ti3Al/TC11 dual alloy specimen were investigated. The results show that after deformation, whatever the deformation amount is, the microhardness value of the transition zone and its two sides are decreased obviously, the differences in microhardness value along the same specimen are reduced significantly and the distribution is relatively homogeneously. In addition, the deformation amount has an obvious effect on the microhardness and element diffusion in the transition zone and its two sides. With the increase of deformation amount, all the value of the microhardness and its distribution homogeneity along the same specimen are increased; the concentration gradients of the alloying elements including Ti, Al and Nb on both sides of the transition zone are decreased, and they diffuse relatively sufficiently along the joining interface. The reason for that is because of larger deformation, the coarse columnar grains formed in laser solid forming are broken sufficiently, the grain boundaries of βphases are disappear, and the αand α2 phases show the fine and equiaxed shape.