Microstructure, Mechanical Properties and Machinability Studies of Al7075/SiC/h-BN Hybrid Nanocomposite Fabricated via Ultrasonic-assisted Squeeze Casting

The present research article deals with the microstructure, mechanical properties and machinability investigation of squeeze-cast Al7075 and Al7075/SiC/h-BN hybrid nanocomposite. The Al7075 alloy nanocomposite has been reinforced by micro-size SiC (1 wt.%) particles and h-BN (0.5 wt.%) nanoparticles, prepared via ultrasonic-assisted melt-stirring approach. In order to achieve the better mixing of reinforcements, diminish the agglomeration effect of nanoparticles and improved wettability of the particles in the melt, SiC and h-BN powders have been ball-milled for the duration of 4 h. The microstructural investigation of the prepared nanocomposite was carried out by using optical microscopy (OM), scanning electron microscopy (SEM) and x-ray mapping analysis. The x-ray mapping and optical microscopic analysis show good dispersion uniformity of reinforcements and refinement in the grain sizes. The investigation of mechanical properties of hybrid nanocomposite shows the significant improvement of about 35.33 %, 21.69 %, 13.87 % and 12.27 % in the offset yield strength, ultimate tensile strength, Rockwell hardness and microhardness (Vickers), respectively. Furthermore, the machinability analysis has been performed to examine the influence of several machining parameters such as cutting speed, feed rate and depth of cut on the surface roughness, cutting force and chips length of the squeeze-cast hybrid nanocomposites under dry and minimum quantity lubrication (MQL) machining conditions. The outcomes of the machinability analysis for hybrid nanocomposites are compared with the Al7075 specimen and discussed.