Thermal Stability and Grain Growth Kinetics of Ultrafine-Grained W with Various Amount of La2O3 Addition

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2020-08, Vol.51 (8), p.4113-4122
• Main Authors: Chen, Zheng, Qin, Mingli, Yang, Junjun, Zhang, Lin, Jia, Baorui, Qu, Xuanhui
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Grain boundaries; Grain growth; Grain size; Lanthanum oxides; Loose powder sintering; Mass transfer; Materials Science; Metallic Materials; Nanotechnology; Structural Materials; Surfaces and Interfaces; Thermal stability; Thin Films; Ultrafines
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-020-05836-8

In this study, ultrafine-grained W alloys with various amount of La 2 O 3 addition (0.5 ~ 5.0 wt pct) have been prepared by pressureless sintering. The influence of the addition of La 2 O 3 particles on the grain growth of ultrafine-grained W alloys have been studied. The results showed that the addition of La 2 O 3 particles can significantly decrease the grain growth rate, but it seems counterintuitive that the ultrafine-grained W alloy with 2.0 wt pct La 2 O 3 addition, rather than 5.0 wt pct, has the smallest grain size (1.23 μ m) after annealing at 1900 °C for 6 h. To reveal the abnormal grain growth behavior, the inhibition effect of the size and distribution of La 2 O 3 particles on grain growth was analyzed, suggesting that the excessive addition of La 2 O 3 particles can cause an abnormal increase in grain size duo to the large fraction of intergranular particles, the small-particle spacing and the high mass transfer rate at the grain boundary.