(1. 中南大学 粉末冶金国家重点实验室，长沙 410083；
2. 中南大学 粉末冶金研究院，长沙 410083)
摘 要: 分别采用氩气雾化(Argon atomization, AA)和等离子旋转电极(Plasma rotating electrode process，PREP)两种方法制备具有不同特性的镍基高温合金粉末，然后在相同条件下对两种粉末进行热等静压制备成块体材料(A-HIP及P-HIP)。分别对粉末和块体材料进行显微组织分析和形貌表征，并对热等静压材料在温度为1000~1100 ℃下、应变速率为0.01~1.0 s-1下进行热压缩实验，利用采集的应力、应变参数，通过迭代和线性回归的方法计算热激活能并构建本构方程，并利用所建立的本构方程预测合金在不同应变下的应力。结果表明：PREP粉末表面洁净度、球形度和粒径均匀度要比AA粉末的好，其表面氧含量也相对较低，仅为0.0079%，而AA粉末中氧含量为0.0139%(质量分数)；相比P-HIP，A-HIP中分布着较多的原始颗粒边界和孔洞，原始颗粒边界的主要组成是大尺寸的γ′相和碳氧化物颗粒；A-HIP的平均晶粒尺寸为8.59 μm, P-HIP的平均晶粒尺寸为12.54 μm；A-HIP的强化相γ′的体积分数(43.91%)与P-HIP的强化相γ′体积分数(43.65%)基本相等。两种材料的激活能分别为1012.9 kJ/mol和757.1 kJ/mol，并采用双曲正弦Arrhenius模型构建不同应变下的本构方程并预测不同变形条件下的真应力，其与实验值间的绝对误差分别为6.46%和4.87%。A-HIP在压缩过程出现宏观裂纹，原始颗粒边界是压缩裂纹产生主要因素之一，且裂纹沿原始颗粒边界进行扩展。
关键字: 镍基粉末冶金高温合金；氩气雾化制粉; 旋转电极制粉；热等静压；热模拟；热变形激活能；本构方程
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Research Institute of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:A new Nickel based superalloy powder was fabricated by methods of argon atomization (AA) and plasma rotating electrode process (PREP), followed by hot isostatic pressing (HIP) under the same conditions. Microstructure analyzing of both as-powder and as-HIPed was carried out. The hot compression tests of two different materials were conducted using a thermal simulator under the deformation conditions at temperature range from 1000 to 1100 ℃ and strain rates range of 0.01-1.0 s-1. The deformation activity energy and constitutive equations were established to predict the true stress at different strains under deformation conditions. The results show that the surface cleanliness and homogeneity of the powder prepared by PREP are much better than those prepared by AA. The oxygen content of argon atomization powder is 0.0139% (mass fraction), while the oxygen content of PREP powder is 0.0079%. The prior particle boundary in as-HIPed fabricated by AA is more severe than that by PREP, which consists of γ′ phase with large size, carbides and oxidizes. The average grain size of A-HIP is determined as 8.59 μm, while that of the P-HIP is 12.54 μm. The volume fractions of γ′ phase of A-HIP and P-HIP are 43.92% and 43.65%, respectively. The deformation activation energies are calculated as 1012.9 kJ/mol (for AA) and 852.9 kJ/mol (for PREP), respectively. In addition, the constitutive equations for two alloys are also developed to predict the true stress at different deformation conditions with the absolute error of 6.46% and 4.87%. The PPB is one of the main reasons that leads to the occurrence of cracking, which propagates along the PPB.
Key words: nickel base powder metallurgy superalloy; argon atomization; plasma rotating electrode process; hot isostatic pressing; hot simulation; activation energy; constitutive equation
