Enhanced oxidation resistance of Mo-12Si-8.5B alloys with ZrB2 addition at 1300℃

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2018,（4）
• 页码范围: 635-642
• 页数: 8页
• 语种: 英文

摘要

Mo-12Si-8.5B and Mo-12Si-8.5B-1.0wt％ZrB2 alloys were fabricated using mechanical alloying,followed by hot-pressing.Both alloys exhibited uniform microstructure,with the Mo3Si and MosSiB2 phases distributing dispersedly in the α-Mo matrix.Mo-12Si-8.5B-1.0wt％ZrB2 showed a finer-grained microstructure than Mo-12Si-8.5B alloy owing to the addition ofZrB2.The results of isothermal oxidation tests at 1300℃ in air revealed that Mo-12Si-8.5B and Mo-12Si-8.SB-1.0wt％ZrB2 alloys initially suffered a transient stage with high mass loss due to the volatilization of MoO3,and then achieved a steady stage owing to the formation of a protective borosilicate scale on the alloy surface.Especially,the transient stage ofMo-12Si-8.5B-1.0wt％ZrB2 alloy was shortened to be less than 300 s,and the mass loss of this stage was reduced by at least 88％ compared with that of Mo-12Si-8.5B alloy,indicating a significant improvement in the oxidation resistance.The addition of ZrB2 not only resulted in a continuous borosilicate scale quickly covering the entire base alloy during the transient stage,but also improved the protectiveness of the borosilicate scale of the steady stage by bringing out a large number of ZrO2/ZrSiO4 particles embedded discontinuously in the borosilicate scale,which effectively restricted the inward diffusion of oxygen by acting as diffusion barriers and decreased the thickness of inner oxide layers in particular.