(1. 中南大學(xué) 粉末冶金國家重點實驗室，長沙 410083；
2. 中南大學(xué) 粉末冶金研究院，長沙 410083)
摘 要: 分別采用氬氣霧化(Argon atomization, AA)和等離子旋轉(zhuǎn)電極(Plasma rotating electrode process，PREP)兩種方法制備具有不同特性的鎳基高溫合金粉末，然后在相同條件下對兩種粉末進(jìn)行熱等靜壓制備成塊體材料(A-HIP及P-HIP)。分別對粉末和塊體材料進(jìn)行顯微組織分析和形貌表征，并對熱等靜壓材料在溫度為1000~1100 ℃下、應(yīng)變速率為0.01~1.0 s-1下進(jìn)行熱壓縮實驗，利用采集的應(yīng)力、應(yīng)變參數(shù)，通過迭代和線性回歸的方法計算熱激活能并構(gòu)建本構(gòu)方程，并利用所建立的本構(gòu)方程預(yù)測合金在不同應(yīng)變下的應(yīng)力。結(jié)果表明：PREP粉末表面潔凈度、球形度和粒徑均勻度要比AA粉末的好，其表面氧含量也相對較低，僅為0.0079%，而AA粉末中氧含量為0.0139%(質(zhì)量分?jǐn)?shù))；相比P-HIP，A-HIP中分布著較多的原始顆粒邊界和孔洞，原始顆粒邊界的主要組成是大尺寸的γ′相和碳氧化物顆粒；A-HIP的平均晶粒尺寸為8.59 μm, P-HIP的平均晶粒尺寸為12.54 μm；A-HIP的強化相γ′的體積分?jǐn)?shù)(43.91%)與P-HIP的強化相γ′體積分?jǐn)?shù)(43.65%)基本相等。兩種材料的激活能分別為1012.9 kJ/mol和757.1 kJ/mol，并采用雙曲正弦Arrhenius模型構(gòu)建不同應(yīng)變下的本構(gòu)方程并預(yù)測不同變形條件下的真應(yīng)力，其與實驗值間的絕對誤差分別為6.46%和4.87%。A-HIP在壓縮過程出現(xiàn)宏觀裂紋，原始顆粒邊界是壓縮裂紋產(chǎn)生主要因素之一，且裂紋沿原始顆粒邊界進(jìn)行擴(kuò)展。
關(guān)鍵字: 鎳基粉末冶金高溫合金；氬氣霧化制粉; 旋轉(zhuǎn)電極制粉；熱等靜壓；熱模擬；熱變形激活能；本構(gòu)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
