冷却速度对快速凝固Ti-48Al-4Cr合金组织转变规律及力学性能

Effect of Cooling Rates on Microstructures Evolution and Nanohardness of Rapidly Solidified Ti-48Al-4Cr Alloy

采用单辊旋淬快速凝固设备制备了不同辊速条件下的Ti-48Al-4Cr(原子分数,%)薄带,研究冷却速度对快速凝固Ti-48Al-4Cr合金的组织及力学性能变化规律。结果表明,快速凝固Ti-48Al-4Cr合金凝固在辊速为10和20 m/s时,基体为等轴的γ相,基体中含有少量的B2相、α_2相颗粒和片层组织;辊速进一步增加至30 m/s时,基体转变为α_2相,片层组织消失。快速凝固Ti-48Al-4Cr纳米硬度随着冷却速度的增加而增加,纳米硬度由常规凝固时的5.04±0.09 GPa增加至辊速为30 m/s时的10.48±0.13 GPa。该结果为研究Ti Al合金组织转变,减少Ti Al合金偏析,提高其力学性能提供了基础。

The effect of cooling rates on microstructure of Ti-48Al-4Cr（at%） alloy rapidly solidified at different wheel speeds were experimentally investigated by the single roller melt-spinning technique.The results indicate that after rapid solidification at the wheel speed of 10 and 20 m/s,the microstructures mainly consist of equiaxed γ phase,a few volume fraction of α2,B2 phase particles and lamellar structures in the γ phase matrix.At the wheel speed of 30 m/s,the matrix changes to α2 phase and the lamellar structures disappear.The nanohardness increases with the cooling rate increasing.It enhances from 4.98±0.10 GPa under normal pressure to 7.48±0.16 GPa under 4 GPa.The nanohardness increases from 5.04±0.09 GPa of conventional cast Ti-48 Al alloy to 10.48±0.13 GPa of rapidly solidified Ti-48Al-4Cr alloy with the wheel speed of 30 m/s.This research has provided the basis of further study on the microstructures,reducing the segregation and enhancing the mechanical properties of Ti Al alloy.