纳米氧化镧增强Mo-Si-B合金多重强化效果分析

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

摘要:

结合机械合金化和热压烧结技术制备的多相Mo-12Si-8.5B合金是由钼固溶体（α-Mo）和金属间化合物（Mo3Si和Mo5SiB2）组成的复合材料。合金的微观组织是Mo3Si和Mo5SiB2以颗粒形态弥散分布在具有连续结构α-Mo基体的晶粒内和晶界处。纳米尺度的La2O3颗粒主要分布在Mo-12Si-8.5B合金中α-Mo相的晶粒内，部分存在于Mo3Si和Mo5SiB2颗粒内。纳米La2O3颗粒的掺杂同时细化了α-Mo基体的晶粒和Mo3Si与Mo5SiB2相的颗粒从而使合金具有细小的微观组织，合金内α-Mo、Mo3Si和Mo5SiB2相的平均晶粒或颗粒尺寸均小于1μm。结合微观组织观察及力学性能试验结果，对Mo-12Si-8.5B合金中存在的细晶强化、固溶强化和颗粒强化多重强化效果的耦合作用进行了量化分析。

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.