一种新型镍基粉末高温合金不同状态热变形行为

Thermal Deformation Behavior of Novel Ni-Based PM Superalloy Under Different Initial Conditions

利用扫描电子显微镜、金相显微镜、热压缩试验机、电子背散射衍射仪等研究了一种新型镍基粉末高温合金(WZ-A3)在1150℃热等静压态、热等静压+1150℃热挤压态、热等静压+1130℃热挤压态3种不同状态下显微组织、热变形行为和组织演变。结果表明:WZ-A3材料1150℃热等静压态样品存在部分粉末原始颗粒边界(previous particle boundary,PPB)和粗大γ′相,经1130和1150℃挤压后样品PPB碎化消失,为等轴晶状态。3种状态样品在热压缩过程中均表现出加工硬化-再结晶软化现象。峰值应力热变形激活能分别是861、858和489 kJ/mol。变形温度对样品变形组织影响明显,1150℃,0.001 s-1条件下,热等静压态和热等静压+1130℃热挤压态样品均出现异常晶粒长大。对比3种状态,热等静压+1130℃热挤压态样品变形行为最优。

The microstructure, thermal deformation behavior and microstructure evolution during the thermal deformation of novel Ni-based powder metallurgy(PM) superalloy under different initial conditions(1150 ℃ hot isostatic pressing, 1150 ℃ hot isostatic pressing + 1150 ℃ hot extrusion, 1150 ℃ hot isostatic pressing + 1130 ℃ hot extrusion) were investigated by scanning electron microscope(SEM), optical microscope(OM), Gleeble thermal compression testing machine, and electron backscatter diffractive(EBSD).The results show that the previous particle boundaries(PPBs) and coarse γ′ still remain in the HIP samples and the PPBs disappear in the 1130 and 1150 ℃ hot extrusion samples, which are equiaxed grains. During the thermal deformation process, the work hardening-recrystallization softening phenomenon is observed in these three samples under different conditions. The thermal deformation activation energies of peak stress are 861, 858 and 489 kJ/mol, respectively. The deformation temperature has an obvious effect on the deformation microstructure of the samples. The abnormal grain growth appears in both the hot isostatic pressing and hot isostatic pressing + 1130 ℃ hot extruded samples under the condition of 1150 ℃, 0.001 s-1. Compared with the other two conditions, the sample of 1150 ℃hot isostatic pressing + 1130 ℃ hot extrusion shows the best deformation behavior.