Production of Al–ZrB₂ nano-composites by microwave sintering process

In this research study, nano-ZrB₂ particles were dispersed in aluminum matrix by a Y-shape mixer. The particle size of ZrB₂ powders were <12 nm and the amounts of ZrB₂ reinforcement varied from 5 to 15 %. The mixed powders were compacted by uniaxial cold press. Subsequently the compacted discs were sintered both in the microwave oven for 6, 8, and 10 min, and in the conventional tube furnace with heating rate of 5 °C/min and in temperature range of 580–620 °C for 60 min, in order to compare the effects of two methods on properties of produced Al–ZrB₂ nano-composites. Microwave-assisted sintering method led to the reduction of sintering time to 8 min. In addition relative density of about 98 % has been also obtained by this method. Aluminum metal matrix Nano-composites (Al-MMNCs) samples were characterized by micro-hardness and compression measurements, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Mechanical measurements reveal that the presence of nano-ZrB₂ particles has improved significantly mechanical properties of Al-MMNCs, as ZrB₂ % was equal to 10 %, optimum hardness and compressive strength of 63 (HV) and 270 Mpa were obtained respectively using microwave sintering process.