Physical, Mechanical, and Microstructural Characteristics of Al-MMCs Incorporating Zirconium Diboride Particles Fabricated by Warm Equal Channel Angular Pressing Method

This study evaluated the influence of mechanical milling time on the physical, mechanical, and microstructural properties of Al metal matrix composites (MMCs) incorporating ZrB۲ ceramic reinforcement. The mixing powders of aluminum with zirconium diboride were mechanically milled at different times. Then, the achieved composite powder was heated, compacted, and turned into bulk material by equal channel angular pressing (ECAP) at ۲۵۰°C. SEM micrographs indicated that the size of the obtained particles decreases by increasing the mechanical alloying time by up to ۱۸ hours. However, the particle size has increased after this time. The average size of fine particles reached ۸۲۳nm using mechanical alloying for ۱۸ hours, while coarse particles were ۸µm. The size calculation of crystallites using XRD examination implied that the rate of crystallite size reduction after ۱۲ hours of mechanical alloying is gradually reduced and reached its lowest level after ۱۸ hours. Then, increasing the mechanical alloying time led to an increase in the size of the crystallites and a decrease in the lattice strain. The microstructure of resultant bulk composites has been characterized by optical microscopy (OM) and SEM. The bulk composite samples processed by the ECAP method, with an optimum amount of ZrB۲ (۵ wt.%), had a relative density, hardness, shear yield stress, and ultimate shear strength of ۹۹.۳%, ۱۷۰ HV, ۱۲۵ MPa and ۱۵۱ MPa, respectively, utilizing powders which were mechanically milled for ۲۴ hours.

کلیدواژه ها:

Al Metal Matrix Composites ، Mechanical milling ، Equal Channel Angular Pressing ، physical properties ، Zirconium Diboride Ceramic Particles ، Microstructural Analysis