Elaborating strengthen mechanism of Pt–Ir solid solution superalloy at finite temperature
Wei Yu, Xiaoyu Chong, Yunxuan Zhou, Mengdi Gan, Ying-Xue Liang, Yan Wei, Aimin Zhang, Chang-Yi Hu, Xingyu Gao, Li Chen, Haifeng Song, Jing Feng
Abstract
Abstract Pt–Ir alloy is potential superalloys used above 1300 °C because of their high strength and creep resistance. However, the ductility of Pt–Ir alloy has rapidly deteriorated with the increase of Ir, resulting in poor machinability. This work quantitatively evaluated the solid solution strengthening (SSS) and grain refinement strengthening (GRS) of Pt–Ir alloy using first‐principles calculations combined with experimental characterization. Here, the stretching force constants in the second nearest neighbor region (SFC 2nd ) of pure Ir (193.7 eV·nm −2 ) are 3.40 times that of pure Pt (57.0 eV·nm −2 ), i.e., the interatomic interaction is greatly enhanced with the increase of Ir content, which leads to the decrease of ductility, and modulus misfit plays a dominant role in SSS. Then, the physical mechanisms responsible for the hardness ( H V ) of Pt–Ir alloy, using the power‐law‐scaled function of electron work function coupled SSS and GRS, are attributed to the electron redistribution caused by different Ir content. Furthermore, a thorough assessment of the thermodynamic characteristics of Pt–Ir binary alloy was conducted, culminating in development of a mapping model that effectively relates composition, temperature and strength. The results revealed that the compressive strength increases with the Ir content, and the highest strength was observed in Pt 0.25 Ir 0.75 . This study provides valuable insights into the Pt–Ir alloy system.