粉末粒度和氧含量对HIP态FGH96合金组织的影响

对氩气雾化法制备的高温合金FGH96粉末进行了热等静压(HIP)处理,分析了粉末粒度和氧含量对HIP态合金组织的影响,研究了FGH96合金组织中PPB的类型、相结构和形成机制。结果表明,氩气雾化FGH96粉末的氧含量较低,平均氧含量约为50×10-6,随着粉末粒度降低,颗粒比表面积增大,促进了粉末氧含量的升高;粉末经HIP处理后氧含量具有遗传特征,原始粉末氧含量越高,HIP态合金氧含量也越高,且平均氧含量增至83×10-6;粉末尺寸和氧含量对合金致密化行为无明显影响,HIP态合金密度约为8.33 g·cm-3。小尺寸粉末制备的HIP态合金原始颗粒边界主要析出ZrO2和MC碳化物,而大尺寸粉末制备的HIP态合金原始颗粒边界主要析出大尺寸花瓣状γ’相和少量MC碳化物。粉末粒度和氧含量影响PPB析出,小尺寸粉末因氧含量高经HIP处理时颗粒边界处存在更多、尺寸更大稳定的ZrO2,ZrO2成为MC碳化物析出形核的核心,促进了大量MC碳化物的析出。

Effect of Size Distribution and Oxygen Content of Powder on Microstructure of HIPed Superalloy FGH96

Nickel-based superalloy FGH96 powders prepared by argon gas atomization were consolidated by hot isostatic pressing(HIP).Type,phase structure and formation mechanism of prior particle boundaries(PPBs) precipitated in HIPed superalloy FGH96 were studied to recognize the effect of powder size distribution and oxygen content on microstructure of HIPed alloy.The results showed that FGH96 powder had low oxygen content with 50×10-6 averagely.With decreasing of the particle size,oxygen content of smaller powder increased with higher specific surface area.Obvious inheritance of oxygen content from powder to HIPed alloy was discovered.HIPed alloy consolidated by powders with high oxygen content always had higher oxygen up to 83×10-6 averagely.The densification phenomenon of the powder did not depend on its size and oxygen content,and the density of the HIPed alloy was about 8.33 g · cm-3.The MC carbides and oxide ZrO2 precipitated preferentially along the particle boundaries for the alloy consolidated by small powders.In contrast,large petal-like γ′ phases and small MC carbides precipitated preferentially at the PPBs for the alloy consolidated by large powders.Furthermore,the formation of PPBs in the HIPed alloy occurred more predominantly by particle size distribution and oxygen content.The elements Zr reacted with the adsorbed oxygen and formed larger and more their highly stable oxide ZrO2 with smaller particles and higher oxygen content.The oxide ZrO2 as the nuclei accelerated the preferential precipitation of MC-type carbides along the particle boundaries during HIP processes.