Qin Zijun, Li Qianyi, Wang Guowei, Liu Feng
The State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China.
Materials (Basel). 2023 Jun 28;16(13):4664. doi: 10.3390/ma16134664.
This research investigates the microstructure and defects of powder metallurgy (PM) nickel-based superalloys prepared by spark plasma sintering (SPS). The densification, microstructural evolution, and precipitate phase evolution processes of FGH96 superalloy after powder heat treatment (PHT) and sintering via SPS are specifically analyzed. Experimental results demonstrate that SPS technology, when applied to sinter at the sub-solidus temperature of the γ' phase, effectively mitigates the formation of a prior particle boundary (PPB). Based on experimental and computational findings, it has been determined that the presence of elemental segregation and AlO oxides on the surface of pre-alloyed powders leads to the preferential precipitation of MC-type carbides and AlO and ZrO oxides in the sintering necks during the hot consolidation process, resulting in the formation of PPB. This study contributes to the understanding of microstructural modifications achieved through SPS technology, providing crucial information for optimizing sintering conditions and reducing the widespread occurrence of PPB, ultimately enhancing the material performance of PM nickel-based superalloys.
本研究调查了通过放电等离子烧结（SPS）制备的粉末冶金（PM）镍基高温合金的微观结构和缺陷。具体分析了FGH96高温合金在粉末热处理（PHT）和通过SPS烧结后的致密化、微观结构演变以及析出相演变过程。实验结果表明，当SPS技术应用于在γ'相的亚固相线温度下进行烧结时，能有效减轻原始颗粒边界（PPB）的形成。基于实验和计算结果，已确定预合金粉末表面存在元素偏析和AlO氧化物会导致在热固结过程中MC型碳化物以及AlO和ZrO氧化物在烧结颈中优先析出，从而导致PPB的形成。本研究有助于理解通过SPS技术实现的微观结构改性，为优化烧结条件和减少PPB的普遍出现提供关键信息，最终提高PM镍基高温合金的材料性能。
