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摘要
Nb-16Si refractory alloy was prepared by mechanical milling and hot-press sintering from high-purity Nb and Si powders. The milling process was carried out in a planetary ball mill for 24 h. The milled powders were consolidated by hot pressing in the argon atmosphere at 30 MPa and 1500 degrees C for 1 h. The powders ball-trilled and material hot-pressed were characterized by XRD and SEM. The size of milled particles was refined and the Si atoms were dissolved into the Nb lattice to form interstitial solid solution. The results reveal that Nb-16Si refractory alloy consists of Nb solid solution (Nb(ss)), Nb(5)Si(3), Nb(3)Si and another Nb solid solution (Nb(ssI)) with high Si content. The average grain size is about 2 mu m and the grains are nearly equiaxed. The predominant fracture mode is transgranular fracture with river patterns in Nb(ss) and relatively flat cleavage planes in silicides. Nano-hardness values of Nb(5)Si(3), Nb(3)Si and Nb(ss) determined by nano-indentation are 13.9, 12.7 and 4 GPa, respectively. The fracture toughness of the alloy reaches 10.98 MPa.m(1/2), indicating ductile phase toughening plays a positive role in improving the fracture toughness. A model of trust chamber was fabricated by sinter-forging and its microstructure is similar to the hot-pressed material.
- 出版日期2009-9-11
- 单位哈尔滨工业大学
