Effect of Nb and Nb5Si3 Powder Size on Microstructure and Fracture Behavior of an Nb-16Si Alloy Fabricated by Spark Plasma Sintering
Effect of Nb and Nb5Si3 Powder Size on Microstructure and Fracture Behavior of an Nb-16Si Alloy Fabricated by Spark Plasma Sintering
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DOI：
10.1007/s11661-014-2378-y
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Wei Liu-;J. Sha
中科院分区：
文献类型：
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作者：
Wei Liu-;J. Sha
研究了Nb和Nb5Si3粉末尺寸（Nb: 83.8、37.4、4.9μm; Nb5Si3: 86.4、43.6、2.9μm）对放电等离子烧结Nb- 16si合金组织和断裂行为的影响。结果表明：所有烧结试样均由Nb和nb5si3相组成，在SPS过程中未形成新相；烧结试样中Nb和nb5si3相的形貌取决于初始Nb和nb5si3粉末的粒度。86.4 μm和43.6μm的nb5si3粉末与上述尺寸的Nb粉末结合，形成Nb基体+ nb5si3岛状双相组织，具有优异的断裂韧性。由细Nb粉（4.9μm）和粗nb5si3粉（86.4μm）组成的显微组织通过小Nb晶粒的韧窝、撕裂和解理混合断裂机制获得了12.4 MPa m1/2的高断裂韧性。当nb5si3粉末尺寸减小到2.9μm时，试样倾向于形成nb5si3基体+ Nb岛双相组织，由于裂纹主要在脆性nb5si3相内扩展，试样的断裂韧性值较差，在5.6 ~ 8.0 MPa m1/2之间。
The influence of Nb and Nb5Si3powder sizes (Nb: 83.8, 37.4, 4.9μm; Nb5Si3: 86.4, 43.6, 2.9μm) on microstructure and fracture behavior of an Nb-16Si alloy fabricated by spark plasma sintering (SPS) was investigated. The results revealed that all as-sintered samples consisted of Nb and Nb5Si3phases, with no new phases formed during SPS. The morphologies of the Nb and Nb5Si3phases in the as-sintered samples depended on the original Nb and Nb5Si3powder sizes. Large Nb5Si3powders 86.4 and 43.6μm in combination with Nb powder of described sizes resulted in an Nb matrix plus Nb5Si3island biphase microstructure, which supplied excellent fracture toughness. The microstructure made from the finest Nb powder (4.9μm) and the largest Nb5Si3powder (86.4μm) had a high fracture toughness of 12.4 MPa m1/2through a mixed fracture mechanism of dimple, tear, and cleavage from the small Nb grains. When the Nb5Si3powder size was decreased to 2.9μm, the sample tended to form an Nb5Si3matrix plus Nb island biphase microstructure, which exhibited a poor fracture toughness value of between 5.6 and 8.0 MPa m1/2due to the crack propagation mainly within the brittle Nb5Si3phase.