Ni_3Al基MX246A合金的应力-应变曲线及加工图

在MTS810试验机上进行了MX246A合金的热压缩试验,获得了不同变形条件下该合金的真应力-真应变曲线,建立了MX246A合金的热加工图。结果表明,Ni3Al基MX246A合金的流变应力随着变形程度的增加先达到峰值应力,之后逐渐降低,趋于稳态流变。在较高的应变速率变形时容易达到稳态流变,在较低的应变速率时,随着应变量从临界应变逐渐增大,流变应力单调递减,并且随着温度的升高,单调递减的速率逐渐增大。真应变量为0.7的MX246A合金的加工图上存在一个安全加工区,对应的温度在1 220℃附近,应变速率在0.001s-1附近。随着真应变量的增大,功率耗散峰值区域逐渐向高温区移动,功率耗散的微观机制随之由动态回复向γ′相的回溶转变。

Stress-Strain Curve and Processing Map for Ni3Al-Based MX246A Alloy

The hot compression tests for MX246A alloy were conducted on MTS810 test machine. True stress-strain curves were obtained and processing maps were constructed. The true stress-strain curves show that MX246A alloy exhibits peak stress at the critical strain followed by flow softening. Moreover, the flow stress is easier to get steady stage at high strain rate while it monotonely decreases at low strain rate with the strain increasing from critical strain, and the decreasing rate increases with elevating temperature. There is one safe working area on the processing map for MX246A alloy with the true strain of 0. 7, where the strain rate is near 0. 001s-1 and the temperature is about 1220℃. The peak efficiency domain of power dissipation moves toward high temperature region with increasing true strain and the corresponding power-dissipation mechanism shifts from dynamic recovery to the solution of γ′ .