燃烧合成Mg2Ni的固相扩散-溶解-析出机理

采用自蔓延燃烧模式及热爆燃烧模式合成较纯的Mg2Ni金属间化合物。通过对不同预热温度下热爆反应过程的研究,证实在较低温度下,Mg-Ni体系存在固固反应,且反应的程度随预热速度的降低而增大。由于Mg-Ni体系为弱放热体系,因此燃烧过程为不完全燃烧。采用试样顶部添加引燃剂(Al-Ti-C)的方法,成功淬熄了Mg-Ni反应。对不同区域进行的SEM、EDS和XRD分析表明反应直接生成了Mg2Ni而没有中间相。

Solid-state diffusion-dissolution-precipitation mechanism of combustion synthesis of Mg2Ni

The pure Mg_2Ni intermetallic was synthesized by self-propagating combustion mode,and thermal explosion mode,respectively.And the reaction process of thermal explosion was researched under different preheat temperatures.The results show that solid combustion exists at lower temperatures,and the reaction extent increases with decreasing preheat rate.Further more,the synthesis is incomplete for the weak exothermal system.A further experiment of combustion front quenching(CFQ) was brought to success in cylindrical steel die by adding some Al-Ti-C powder that was accepted high exothermic system on the top of Mg-Ni specimen.The phase structure changes of all region in the quenched sample during the combustion synthesis were observed by scanning electron microscopy,energy-dispersive spectroscopy and X-ray diffractometry.The results show that the synthesis of Mg_2Ni is direct rather than through other intermediates.