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针对高化学活性超轻Mg-Li合金的特点与存在的问题,提出了以高稳定性且综合性能好的MgO和Mg_2Si粒子为增强相,并采用液态反应合成技术制备Mg-Li基复合材料的设想。确定了最佳反应添加物种类、尺寸及加入方法,形成了相应的制备工艺和装备。以光学显微镜、SEM、TEM及X射线衍射对复合材料的相组成、形态及界面结构进行了全面分析,证明反应生成的粒子尺寸细小(0.5～5μm)、分布均匀;粒子与基体界面清晰,无过渡层和其它附加物,界面结合良好。系统地研完了该复合材料增强相反应热力学和微观动力学机制,建立了SiO_2与Mg-Li合金熔体反应的动力学模型,认为MgO在SiO_2与熔体界面处反应生成,而Mg_2Si形成于熔体中较高的Mg和Si浓度处,得出了SiO_2反应速度表达式。对复合材料的常规力学性能及抗蠕变性能进行了测试,所制备的复合材料强度、弹性模量及硬度大幅度提高,延伸率虽降低但可达到5％以上;该复合材料抗蠕变性显著提高,且随温度的升高效果更明显;较好地解决了Mg-Li合金抗蠕变性差及热稳定性差的问题。并结合动态拉伸原位观察结果探讨了其强化机制。 给出了粒子进入熔体的临界条件,定量描述了考虑粒子浓度时粒子在熔体中的运动速度,建立了粒子俘获/推移的热力学条件及粒子俘获的临界速度判据。为粒子增强复合材料?
In view of the characteristics and existing problems of high chemical active ultra-light Mg-Li alloy, MgO and Mg_2Si particles with high stability and good comprehensive properties are proposed as reinforcing phases, and the liquid reaction synthesis technique is used to prepare Mg-Li matrix composites Imagine. The type, size and adding method of the best reaction additive were determined, and the corresponding preparation technology and equipment were formed. The phase composition, morphology and interfacial structure of the composites were analyzed by optical microscope, SEM, TEM and X-ray diffraction. The results showed that the size of the particles was small (0.5 ~ 5μm) and distributed uniformly. The interface between the particles and the matrix was clear, Transition layer and other addenda, the interface is well bonded. The thermodynamic and microscopic kinetic mechanism of the phase reaction was systematically studied. The kinetic model of the reaction between SiO_2 and Mg-Li alloy was established. It is believed that MgO reacts at the interface between SiO_2 and melt, and Mg_2Si forms in the melt At higher Mg and Si concentrations, the expression of SiO 2 reaction rate was obtained. The mechanical properties and creep resistance of the composites were tested. The strength, elastic modulus and hardness of the composites were greatly improved, while the elongation rate was reduced to 5%. The creep resistance Significantly increased, and with the temperature increase effect is more obvious; better solved the creep resistance of Mg-Li alloy poor and poor thermal stability problems. Combined with the results of dynamic stretching in situ observation of its strengthening mechanism. The critical conditions for particles to enter the melt are given. The velocity of the particles in the melt is considered quantitatively when the particle concentration is considered. The thermodynamic conditions of particle capture / transport and the criterions of the critical velocity of particle trapping are established. Particle reinforced composite material?