Phase and microstructural characterization of Mo–Si–B multiphase intermetallic alloys produced by pressureless sintering
Phase and microstructural characterization of Mo–Si–B multiphase intermetallic alloys produced by pressureless sintering
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DOI：
10.1016/j.jallcom.2013.08.107
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发表时间：
2014-01
影响因子：
6.2
通讯作者：
P. R. Taleghani;S. Bakhshi;G. H. Borhani;M. Erfanmanesh
中科院分区：
文献类型：
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作者：
P. R. Taleghani;S. Bakhshi;G. H. Borhani;M. Erfanmanesh
本研究将Mo-47Si-23B和Mo-57Si-10B粉末（at.%）在磨耗器球磨机中研磨20 h，转速为365转/分，球粉质量比为20/1。将机械合金粉末在450℃脱气后，在600 MPa压力下压成直径为25 mm的圆柱形样品。采用管式电阻炉在氩气气氛下对样品进行了烧结。采用扫描电子显微镜、x射线衍射仪和能谱仪研究了机械合金粉末和烧结试样的物相和显微组织特征。并进行了硬度试验。经1400℃烧结2 h可制得具有MoB和mosi2优势相的Mo-57Si-10B合金，1300℃烧结3 h可制得与1400℃烧结2 h的Mo-57Si-10B合金相似的优势相，但MoB相的体积分数不同。与Mo-57Si-10B合金相比，Mo-47Si-23B合金含有更高的MoB化合物相分数。在Mo-47Si-23B合金中，由于含有大量的MoB相，合金的密度非常高。MoB的形成热作为正势，增加了烧结驱动力，从而提高了堆积密度。最后，Mo-47Si-23B合金显微组织中mosi2颗粒在MoB连续基体中均匀细小分布，硬度可达660维氏。
In this study Mo–47Si–23B and Mo–57Si–10B powders (at.%) was milled for 20 h in attritor ball mill with a rotational speed of 365 rpm and the ball/powder mass ratio 20/1. After degassing of As-mechanically alloyed powders at 450 °C, the powders were pressed into cylindrical samples with 25 mm diameter under 600 MPa pressure. The samples were sintered by using of a tube resistance furnace under Ar atmosphere. Phase and microstructure characteristic of mechanically alloyed powders and sintered samples, were investigated by scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. Also hardness test was performed. Homogeneous distribution of active and ultra-fine powders were obtained after milling for 20 h. Mo–57Si–10B alloy with MoB and MoSi2dominant phases was produced by sintering at 1400 °C for 2 h. Dominant phases similar to Mo–57Si–10B alloy sintered at 1400 °C for 2 h could be synthesized in Mo–47Si–23B alloy after sintering at 1300 °C for 3 h, but volume fraction of MoB phase was different. The Mo–47Si–23B alloy contained a higher phase fraction of MoB compound as compared to Mo–57Si–10B alloy. Very high density in Mo–47Si–23B alloys was obtained, due to the presence of high volume fraction of MoB phase. Formation heat of MoB acted as a positive potential to increase driving force of sintering and consequently bulk density. Finally, a uniform and fine distribution of MoSi2particles in MoB continuous matrix in the microstructure of Mo-47Si-23B alloys led to the high hardness up to 660 Vickers.