一种含铁Ni_3Al基合金的热变形行为

采用Gleeble-1500D热模拟试验机对一种含铁Ni3Al基合金进行了高温压缩试验,试验温度为1 050~1 150℃,应变速率为0.1~1.0s-1,工程应变量为50%。获得了不同变形条件下的真应力-真应变曲线,并分析了合金微观组织的变化。结果表明: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。提高变形温度及减小应变速率能有效促进动态再结晶过程。在变形温度1 100℃以上,工程应变为50%时,能够获得完全再结晶的锻态组织。基体中的γ′相粒子对合金动态再结晶有抑制作用,β相的存在促进了相界处动态再结晶形核但抑制了完全动态再结晶晶粒的长大。高温下β相的软化效应和γ′相的回溶转变都有效提高了Ni3Al基合金热加工性能。

Hot deformation behavior of a Ni3Al-Fe alloy

Hot compression tests with engineering strain of 50% of a Ni3Al-Fe superalloy were conducted by Gleeble-1500D thermal simulating tester at deformation temperatures from 1050 to 1150?? and strain rates from 0. 1 to 1. 0s-1. True stress-strain curves were obtained and the microstructures of alloy were also analyzed. The results show that the flow stress of the alloy exhibits a peak stress at the critical strain followed by flow softening. At last, the flow stress tends to reach a steady stage. The dynamic recrystallization process of this alloy can be effectively promoted by increasing deformation temperature and decreasing strain rate. When deformation temperature is higher than 1100?? and engineering strain is 50%,completely recrystallized microstructure can be obtained.?á? particles in the matrix have inhibitory effect on dynamic recrystallization. The nucleation of dynamic recrystallization primarily occurs at the interface of ?? phase and the matrix. However???? phase restrains the growth of completely dynamic recrystallized grains. At high temperature, both the softening effect of ?? phase and the solution of ?á? phase can effectively improve the hot workability of the alloy.