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以元素粉末为原料,在自制燃烧合成装置中,采用燃烧波前沿淬熄法,并结合X射线衍射、扫描电镜观察和微区成分(EDAX)分析等手段,对Ni-Al、Fe-Al和Ti-Al三种铝化物的宏观燃烧学特征,以及相应产物组织结构形成规律进行了系统的测试分析与讨论。 研究发现,三种铝化物中的燃烧反应都是从铝熔化后开始,其内部组织结构转变与燃烧反应同步进行,而且所有合金中的燃烧反应都是先形成富铝化合物,然后富铝初始反应产物再通过一系列中间过渡反应向最终反应产物转化,这些在瞬间发生的一系列复杂反应过程可分解成液-固反应和后续固-固反应两个主要阶段,其中铝熔化与铺展具有很高的质量传递速度,因而铝熔化后先形成的液-固反应属于主燃烧过程,其快速反应放热与升温保证了燃烧过程的持续进行,是关系到燃烧波能否稳定扩展的重要过程,而后续固-固反应则是通过扩散使中间过渡反应产物向最终合成产物转化的后烧反应阶段。 由于组元间相互作用能力的差异,本研究工作试验三种合金中的反应速度与反应程度并不相同,其最终合成产物对平衡态的偏离程度也不相同;此外,高温燃烧反应产物在冷却相变中也可能偏离平衡态,这些都可使合成产物具有亚稳态结构。 对目前广泛使用的燃烧波稳定扩展T_(ad)判据(即认为只有T_(ad)>1800K的合成体系中?
In the home-made combustion synthesis device, the front-end quenching method of combustion wave was used to synthesize Ni-Al, Fe-Al and Fe-Al powders with elemental powder as raw material. Combining with X-ray diffraction, scanning electron microscopy and EDAX analysis, Ti-Al three aluminates macroscopic combustion characteristics, as well as the formation of the corresponding structure of the product structure of a systematic analysis of the test and discussion. It was found that the combustion reactions in all three aluminides started from the melting of aluminum and the transformation of their internal structure and combustion reaction proceeded synchronously. The combustion reactions in all the alloys were the formation of aluminum-rich compounds and then the initial reaction of aluminum-rich The product is then converted to the final reaction product through a series of intermediate transition reactions. The series of complex reaction processes occurring in an instant can be decomposed into two main phases: liquid-solid reaction and subsequent solid-solid reaction. Aluminum melts and spreads very high Of the mass transfer rate, so the aluminum melt formed after the liquid-solid reaction belongs to the main combustion process, its rapid reaction exothermic and warming to ensure the continued combustion process is related to the stability of the expansion of the combustion process an important process, and Subsequent solid-solid reaction is through the diffusion of intermediate transition reaction products to the final synthesis of the conversion reaction after the reaction stage. Due to the differences in the ability of interaction between the components, the reaction speed and the degree of reaction in the three alloys tested in this research work are not the same, and the final synthesized products have different degrees of deviation from the equilibrium state. In addition, Phase transition may also deviate from the equilibrium state, which can make the product has a metastable structure. For the widely used combustion wave stable expansion T_ (ad) criterion (that is, only T_ (ad)> 1800K synthesis system?