Nb-Si-Mo三元系合金相图

 Nb/Nb5Si3原位复合材料是一种有望替代镍基超合金用做飞机发动机叶片的新一代超高温结构材料。采用非自耗电弧熔炼技术制备出不同成分的Nb/Nb5Si3原位复合材料，利用X射线衍射仪、扫描电镜和能谱仪对Nb-Si-Mo三元系合金的相组成和微观组织进行研究。结果表明：Nb-Si-Mo三元系部分液相面投影图（<37.5 at% Si）含有4个初生相区，其立体相图中存在2个液固四相平衡反应和1个固态四相平衡反应。在2个液固四相平衡反应面之间存在一个三相共晶平衡棱柱，成分位于该棱柱内的合金会通过L→Nbss+β-Nb5Si3反应凝固生成Nbss/β-Nb5Si3片层共晶。

Phase Diagram of Nb-Si-Mo Ternary System

Nb/Nb5Si3 in-situ composites show great potential to replace Ni-based superalloys as a new generation of ultra-high temperature structural materials for aircraft engines. In the present study, Nb/Nb5Si3 in-situ composites with different compositions are prepared by non-consumable arc-melting technology. Constituent phase and microstructure of Nb-Si-Mo ternary alloys are investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results indicate that partial liquidus surface projection of Nb-Si-Mo ternary system (<37.5 at% Si) contains four primary phase regions. Two liquid-solid four-phase equilibrium reactions and one solid four-phase equilibrium reaction appear in three-dimensional phase diagram. Between the two liquid-solid four-phase equilibrium surfaces, there exists a three-phase eutectic equilibrium region, the alloys in which solidify into Nbss/β-Nb5Si3lamellar eutectic by L→Nbss+β-Nb5Si3 reaction.