Mo-Si合金室温及高温拉伸力学性能研究

Tensile Properties of Mo-Si Alloys at Room and Elevated Temperature

采用粉末冶金技术制备了不同Si含量(0,0.1,0.3wt%Si)的Mo-Si合金板材,并在25,300,800和1200℃下进行了静拉伸试验,研究了试验温度对Mo-Si合金板材力学性能、断裂方式及微观组织的影响。结果表明:随试验温度升高,纯钼及Mo-Si合金板材强度明显下降,但延伸率以300℃为分界点呈现出先升后降的趋势。室温下Mo-Si合金的断裂方式为穿晶解理断裂,在300及800℃时主要为韧窝延性断裂,而1200℃时为沿晶断裂。对Mo-Si合金强化机制的分析表明,室温下的强化主要来源于弥散强化和固溶强化,而在高温时,固溶作用明显减弱,颗粒弥散和粗化晶粒为主要的强化手段。

The Mo-Si alloy sheets with different silicon contents were fabricated by powder-metallurgical processing, and static tensile tests were performed at 25,300, 800 and 1200 ℃, respectively. The effect of test temperatures on mechanical properties, facture mode and microstructure of Mo-Si alloys were studied. The results indicate that with increasing of tensile test temperature, the strength of the pure Mo and Mo-Si alloy sheets decrease dramatically, the elongation shows an increasing trend at lower 300 ℃ and then decreasing at higher temperatures. The fracture mode of molybdenum alloy sheets transform from transgranular cleavage fracture at room temperature to dimple fracture at 300 and 800 ℃, and then to intergranular fracture at 1200 ℃. The strengthening mechanism analysis results show that the strengthening of Mo-Si alloy originates from particle dispersion strengthening and solid solution strengthening at room temperature. While, at elevated temperature the role of solid solution strengthening weakens significantly and the particle dispersion strengthening and grain coarsening are main strengthening modes.