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Synthesis of a novel MoSS+Mo5SiB2+Mo5Si3 based Mo–Si–B alloy and its enhanced fracture toughness

2022; Elsevier BV; Volume: 203; Linguagem: Inglês

10.1016/j.vacuum.2022.111278

1879-2715

Tao Yang, Jianbo Wu, Min Huang, Zhu Liu, Jinfang Wang, Tianle Wang, Yihang Fang, Zixin Yan, Vladimir Levchenko,

MXene and MAX Phase Materials

Mo–Si–B based alloys are promising ultrahigh-temperature structural materials for turbine blades. Different from traditional MoSS (Mo solid solution)+Mo5SiB2+Mo3Si based alloy, present paper focuses on a novel non-equilibrium MoSS + Mo5SiB2+Mo5Si3 based alloy, which shows more potential for excellent comprehensive performance. This alloy was synthesized by SPS (spark plasma sintering) technique using pure Mo and Mo5SiB2+Mo5Si3 powders as raw materials. SEM, EDS, XRD, EPMA, single-edge notched bending and nano-identation tests were used to reveal the formation mechanism of this alloy and evaluate its fracture toughness. The results showed that this MoSS + Mo5SiB2+Mo5Si3 based alloy was composed of MoSS, Mo5SiB2, Mo5Si3 and a little Mo3Si. Mo5SiB2+Mo3Si halos were found around the original Mo5SiB2+Mo5Si3 particles as a result of inter-diffusion between Mo and Mo5SiB2+Mo5Si3 during sintering processes. Compared with traditional cast or reaction sintered MoSS + Mo5SiB2+Mo3Si based alloy with the same composition, this MoSS + Mo5SiB2+Mo5Si3 based alloy showed superior fracture toughness benefiting from its higher MoSS content, larger coarseness of MoSS and lower Si concentration in MoSS.