连续温度梯度热处理Ti−5Al−5Mo−5V−3Cr合金的显微组织演变与力学性能

摘要

采用一种新型高通量实验方法,实现对Ti-5553合金(Ti?5Al?5Mo?5V?3Cr,质量分数,％)在600～700℃范围内的连续温度梯度热处理.实验通过对圆台形样品进行直流电加热,由于截面面积不同而导致电流热效应不同,从而使样品表面温度呈梯度变化.采用端淬实验实现Ti-5553合金的连续冷却速率变化,研究合金在不同热处理条件下的显微组织演变和力学性能.结果表明:Ti-5553合金的伪调幅分解温度为(617±1)℃,析出的α相尺寸在300 nm左右;合金在伪调幅分解温度下时效4 h达到最高的硬度.因此,这种高通量方法能够快速准确地判断合金中相转变温度以及相应的组织转变.%A new high throughput heat-treatment method with a continuous temperature gradient between 600 and 700℃ was utilized on the Ti-5553 alloy (Ti?5Al?5Mo?5V?3Cr, mass fraction, ％). The temperature gradient was induced by the variation of the axial section of sample, which was heated by the direct current. The variation of continuous cooling rates on the treated sample was realized by using the end quenching method. The microstructural evolution and mechanical properties under different heat treatment conditions were evaluated. The results show that the pseudo-spinodal decomposition of the alloy occurs at (617±1)℃, and the size of the precipitatedα phase is around 300 nm. Moreover, the highest microhardness is obtained after the heat treatment at the pseudo-spinodal decomposition temperature for 4 h. These indicate that the high throughput method is efficient and fast to determine the phase transformation temperature and corresponding microstructural evolution of alloys.