Bimodal Mo-12Si-8.5B-1.0wt%ZrB₂ alloys were fabricated via hot pressing sintering of a mixture of mechanical alloying Mo-Si-B-ZrB₂ powders and unmechanical alloying Mo-Si-B-ZrB₂ powders in selected proportion. The bimodal Mo-12Si-8.5B-1.0wt%ZrB₂ alloys consisted of fine and coarse α-Mo grains, showing mainly bimodal structure with a part of submicron-scaled α-Mo grains and partial micron-scaled α-Mo grains, where the intermetallics showed weak bimodal distribution but with fine grain structure. Oxidation behavior of the alloys was studied at 1100 °C in air. When average grain sizes of the fine and coarse α-Mo grains in the bimodal alloy were 0.45 μm and 2.15 μm, respectively, and their volume fraction ratio was approximately 1.7:1, a superior oxidation resistant property was achieved. Its mass loss in the transient stage was decreased, showing a 62% decrease compared to that of the ultrafine-grained alloy, and the oxidation recession rate of the alloy substrate was decreased significantly. Additionally, a thinner borosilicate glass scale was formed after oxidation for 30 h which exhibited excellent protective capability. The improved oxidation resistance at 1100 °C was mainly because of the combination of lower oxidation rate of the coarser α-Mo grains and the higher lateral flow rate of the borosilicate glass due to the presence of partial fine α-Mo grains and intermetallics.

双峰的Mo-125 I-8.5B-1.0重量％的ZrB ₂合金通过热压烧结机械合金化的Mo-Si系B-的ZrB的混合物制成₂粉末和合金化unmechanical钼的Si-B-的ZrB _2种在选定的比例粉末。双峰Mo-12Si-8.5B-1.0wt％ZrB ₂合金由细和粗的α-Mo晶粒组成，主要表现为双峰结构，部分为亚微米级的α-Mo晶粒，部分为微米级的α-Mo晶粒，其中金属间化合物显示出较弱的双峰分布，但具有细晶粒结构。在1100°C的空气中研究了合金的氧化行为。当双峰合金中的细α-Mo晶粒和粗α-Mo晶粒的平均晶粒尺寸分别为0.45μm和2.15μm，并且它们的体积分数比约为1.7：1时，获得了优异的抗氧化性能。其在过渡阶段的质量损失减少了，与超细晶粒合金相比减少了62％，并且合金基体的氧化衰退率显着降低。此外，氧化30小时后，形成了更薄的硼硅酸盐玻璃鳞片，显示出优异的保护能力。1100°C下抗氧化性的提高主要是由于存在较细的α-Mo细颗粒和金属间化合物，使较粗的α-Mo晶粒的氧化速率较低，而硼硅玻璃的横向流速较高。