Multiple strengthening effects of Mo-Si-B alloy enhanced by nanoscale La2O3 particle

Abstract:

Multi-phases Mo-Si-B alloy prepared using mechanical alloying (MA) followed by hot pressing is the composite material which consists of a ductile α-Mo solid solution and the high-strengthed Mo3Si and Mo5SiB2 intermetallics. The microstructure exhibits that the spherical Mo3Si and Mo5SiB2 particles distribute within the grain and along with the grain boundary of the continuous and uniform α-Mo matrix. Some nanoscale La2O3 particles also are mainly dispersed in the α-Mo grain and partially in the Mo3Si and Mo5SiB2 intermetallic particles. These La2O3 particles can refine the grain sizes or particle sizes of α-Mo matrix and intermetallic, which promotes the alloy to obtain a fine-grained microstructure. The average grain sizes or particle sizes of α-Mo, Mo3Si and Mo5SiB2 phases are only sub-microns in size. The strengthening mechanisms include fine grain strengthening, solution strengthening and particles strengthening are quantitatively analyzed, which combines the microstructure and the mechanical test results.