旋锻W-Y?O?合金在1400~1600℃高温拉伸蠕变行为研究

Study on the Tensile Creep Behavior of Swaged W-Y?O? Alloy at High Temperatures of 1400–1600°C

摘要:

研究了粉末冶金和高温旋锻制备的Y?O?弥散强化钨(W-Y?O?)合金在1400~1600℃/150~180MPa的拉伸蠕变行为。并与商业轧制纯钨的性能进行了对比。采用电子扫描显微镜(SEM)、电子背散射衍射(EBSD)和透射电子显微镜(TEM)分析了蠕变前后样品晶粒、第二相颗粒、位错等的变化。实验结果表明,旋锻W- Y?O?合金的蠕变性能优于轧制纯钨,其稳态蠕变率为8.22×10e-7~1.76×10e-4,较轧制纯钨低2个数量级；其主要原因在于W- Y?O?合金的纳米级和亚微米级的弥散颗粒能够钉扎晶界和位错运动,同时,W- Y?O?较大晶粒长径比减弱了扩散蠕变。随着温度和蠕变应力的提高,第二相粒子发生团聚,导致钉扎效应减弱,晶粒长径比减小,原子扩散和再结晶导致的晶界滑移主导的蠕变机制占比逐渐增大,但旋锻W- Y?O?主体上仍表现为位错运动控制。

Abstract:

The tensile creep behavior of Y?O?-dispersion-strengthened tungsten (W-Y?O?) alloys prepared via powder metallurgy and high-temperature rotary swaging was investigated at temperatures ranging from 1400 to 1600°C under pressures of 150 to 180 MPa. Changes in grain structure, second-phase particles, and dislocations before and after creep were analyzed using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM).Experimental results indicate that the creep performance of rotary-forged W-Y?O? alloys surpasses that of rolled pure tungsten, with a steady-state creep rate ranging from 8.22×10e-7 to 1.76×10e-4—two orders of magnitude lower than rolled pure tungsten. The superior creep performance of rotary-forged W-Y?O? primarily stems from the pinning of grain boundaries and dislocation motion by nanoscale and submicron-sized Y?O? particles, coupled with the suppression of diffusion creep due to thelarger grain aspect ratio.As temperature and creep stress increase, the agglomeration pinning effect of second-phase particles weakens, reducing the grain aspect ratio. The proportion of creep mechanisms dominated by grain boundary slip due to atomic diffusion and recrystallization gradually increases. However, dislocation motion control remains the primary mechanism in the W-Y?O? matri