Research Of Metallic Glass Particles-reinforced Al-based Composites Explosively Compacted By Mixed Powders And Its Mechanical Properties

Particle reinforced aluminium matrix composits have many excellent properties such as mechanical properties at high temperature, the lower thermal expansion coefficient and wear resistance. The composites are widely applied for the structural materials of high performance which can improve the structural safety or optimize the structural desigh. For the moment, the ceramic powders, such as SiC, Al₂O₃, B₄C and graphite were adopted as the main reinforcement of the composites widely. But the thermal diffusion coefficient of the ceramic is quite different from that of the metal matrix. Compared to the ceramic, the metallic glass reinforcements which contain only metallic element are more compatible with the metal matrix which results in better interface bonding. Therefore, they are considered to be potential substitutes for ceramic reinforcements in MMCs.The main work of the thesis includes: the fabrication of the metallic glass particles-reinforced Al matrix composites by explosive compaction of the mixed powders. The macroscopical and microcosmic mechanism on fabrication of the composites was researched. The quasi-static mechanical properties of the composite was researched and the curve of stress-stain of the composites was obtained. Compared to the monolithic matrix and the conventional ceramic particle reinforced Al matrix composites, the metallic glass reinforced Al matrix composites exhibit the more excellent mechanical properties.Chapter 1: The research content, as well as the research method and background were concisely presented. The evolvement of relative fabrication methods and the properties of the particle reinforced aluminium matrix composits was expounded.Chapter 2: The macroscopic and microscopic theories about the preparation of the metallic glass particles-reinforced metal matrix composites (MMCs) were investigated. The explosive compaction of the mixed tungsten and titanium powders was carried out, and the compaction process was simulated by the finite element method. Based on the ideal fluid model of symmetrically colliding, the angle deformation near the stagnation point of flow field in explosive welding was also calculated.Chapter 3: The experimental research of the explosive compaction of the metallic glass particles-reinforced aluminum matrix composites was carried out. The metallic glass particles-reinforced aluminum matrix composites were prepared sucessfully. The composition, structure and the interface between the amorphous reinforcement and the matrix were tested by means of x-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscope (SEM) etc.Chapter 4: The quasi-static compression mechanical properties of the metallic glass particles-reinforced aluminum matrix MMCs was researched recur to universal testing machine of Instron 3367. Self-consistent theory was adopt to estimate the equivalent elastic modulus of the composite. The numerical simulation of the microscopic mechanical properties of the composites was carried out by LS-DYNA program. Based on the theory and the numerical simulation, the reinforced mechanism of the composite was discussed.Chapter 5: The calculation and the analysis of the temperature rise caused by impact and the microscopic heat transfer during explosive compaction were carried out. The results show that there is a very thin crystallization layer around the amorphous paticle although the temperature rise does not result in the crystallization of the whole amorphous phase during the explosive compaction. Many excellent properties of the metallic glass particles can be maintained, which proves the feasibility of the method of explosive compaction for preparing the metallic glass particles-reinforced MMCs.Chapter 6: The main conclusions and suggestions for the following investigation are given.