Effects of the alloying element on the stacking fault energies of dilute Ir-based superalloys: A comprehensive first-pri
- PDF / 1,141,181 Bytes
- 8 Pages / 584.957 x 782.986 pts Page_size
- 49 Downloads / 184 Views
Effects of the alloying element on the stacking fault energies of dilute Ir-based superalloys: A comprehensive first-principles study Gengsen Xu1 , Xiaoyu Chong1,2,a), Yunxuan Zhou1, Yan Wei3,b), Changyi Hu3, Aimin Zhang3, Rong Zhou1, Jing Feng1 1
Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA 3 Sino-Precious Metals Holding Co., Ltd., Kunming 650093, China a) Address all correspondence to these authors. e-mail: [email protected] b) e-mail: [email protected] 2
Received: 23 June 2020; accepted: 16 September 2020
Iridium (Ir) has an extremely high melting point (2443 °C), high chemical stability and is one of the most promising high-temperature materials. However, Ir is more difficult to process compared with other face-centered cubic metals, such as Ni and Al, which limits its applications. To solve this problem, we study the effect of 32 alloying elements (X) on stacking fault energy of dilute Ir-based alloys generated by shear deformation using the first-principles calculations. The investigation reveals that there are many alloying elements studied herein decrease the stacking fault energy of face-centered cubic (fcc) Ir, and the most effective element in reducing stacking fault energy of fcc Ir is Zn. The microscopic mechanism is caused by electron redistribution in the local stacking fault area. These results are expected to provide valuable guidance for the further design and application of Ir-based alloys.
Introduction Iridium (Ir) has the highest melting point (2443 °C) among the transition metals with the face-centered cubic (fcc) crystal structure [1]. It is widely used in the engine of spacecraft, bonding alloys, thermocouple, and other fields because it has good corrosion and creep resistance, strong oxidation resistance, high shear moduli, and very low Poisson’s ratio [1, 2, 3, 4]. The intrinsic (not caused by impurities) brittle transgranular cleavage and brittle intergranular fracture of Ir result in its brittle fracture at temperature below 1000 °C, which limits its applications [5, 6]. Previous studies have shown that the size misfits exceeding 15% between solvent and solute atoms can cause dendrite segregation [7]. To improve the processing performance of Ir, Liu et al. developed a brand called DOP-26, which has the nominal composition of Ir–0.3W–0.006Th– 0.005Al (wt%) [8]. In DOP-26, W, Th, and Al can improve the formability. Yamabe et al. added Nb and Ti to Ir to realize the refractory superalloys that exhibited very high compressive strengths [9]. Addition of alloying elements is an effective
approach to balance the ductility and the strength. However, the effects of alloying elements on the ductility of Ir have not been systematically studied yet. Dislocation slip is the main form of plastic deformation of metallic materials, including nucleation, movement and interactions between themselves as well as oth
Data Loading...
