Optimization of Multi-phase Mo-12Si-8.5B Alloy by SiC Whisker
Optimization of Multi-phase Mo-12Si-8.5B Alloy by SiC Whisker
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SiC晶须优化多相Mo-12Si-8.5B合金
DOI：
10.1007/s11837-018-3059-x
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发表时间：
2018-11-01
期刊：
影响因子：
2.6
通讯作者：
Zhang, Pingxiang
中科院分区：
文献类型：
--
作者：
Li, Bin;Lin, Xiaohui;Zhang, Pingxiang
细晶和多相Mo-Si-B合金含有许多晶粒/相界面，可以通过改变界面来优化其性能。在组织设计的基础上，介绍了Mo-Si-B多相合金中的SiC晶须。采用液-液掺杂法将SiC晶须混合在机械合金粉末中，采用热压法制备了Mo-12Si-8.5B-SiC合金。实验研究了SiC晶须的显微组织、强度和韧性，并对固相反应和热力学计算进行了分析，以评价SiC晶须的效果。显微组织观察表明，SiC的加入可以显著提高Mo-Si-B合金的金属间化合物含量，降低α-Mo含量，从而调节相组成。这种影响导致组织发生变化，由无sic的Mo-12Si-8.5B合金的连续α-Mo基体转变为Mo-12Si-8.5B- sic合金的细晶金属间基体。SiC的加入使晶界和相界处的SiO2颗粒减少，这主要与晶须与基体界面反应产生的晶界净化作用有关。Mo-Si-B-SiC合金中含有少量二氧化硅的金属间基体具有较高的强度，有利于提高合金的强度和断裂韧性。
Fine-grained and multi-phase Mo-Si-B alloy contains many grain/phase interfaces, which allows for optimizing its performances by modifying its interfaces. Based on the structure design, this study introduces the SiC whisker in a multi-phase Mo-Si-B alloy. The Mo-12Si-8.5B-SiC alloy, which used a liquid–liquid doping method to mix the SiC whiskers in the mechanical alloyed powder, was also synthesised by hot pressing. The microstructure, strength and toughness were experimentally examined, and the solid-state reaction and thermodynamic calculations were analysed to evaluate the effect of the SiC whisker. Microstructural observations showed that the SiC addition could regulate the phase constitution by markedly increasing the intermetallic content and, moreover, decrease the α-Mo content in the Mo-Si-B alloy. This effect resulted in a change in the microstructure, which was transformed from a continuous α-Mo matrix of the SiC-free Mo-12Si-8.5B alloy to a fine-grained intermetallic matrix of the Mo-12Si-8.5B-SiC alloy. Some SiO2 particles distributed at the grain and phase boundaries could be decreased by the SiC addition, which was mainly related to the grain/phase boundary purifying effect derived from the interfacial reactions of the whisker and matrix. The high strength of the intermetallic matrix with a small amount of silica in the Mo-Si-B-SiC alloy is beneficial for enhancing the strength and fracture toughness.