Synthesis, properties and microstructure of sintered and hot extruded boron carbide reinforced AA8079 (Al-Cu-Fe-Si-Zn) matrix composites

Abstract

AA8079 matrix composites contain various weight percentages (0, 5, 10 and 15) of Boron Carbide (B4C) were synthesized via ball milling and powder metallurgy route. Suitable weight percentages of matrix and reinforcement powders were milled for a period of 10 h in a high energy ball milling setup. The uniform distribution of B4C particles in AA8079 matrix was confirmed by characterizing these composite powders by x-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). The ball milled powders were consolidated by cold compaction for a pressure of 400 MPa. Sintering was done at a temperature of 575 °C for a period of 3 h in Argon controlled atmosphere. Hot extrusion was conducted on the sintered samples. The effect of addition of weight percentages of B4C on the microstructure, density, hardness and compressive strength of the sintered and hot extruded composites were studied. As a result, 52% of improvement in hardness and 39.2% of improvement in compressive strength was observed for the addition of 15 wt % of B4C in AA8079 matrix. The 82% of improvement in compressive strength was observed for extruded composite compared with sintered one. The improvement in microstructure, hardness, density and compressive strength were obtained for the hot extruded composites when compared with sintered composites. SEM fractographic analysis was performed on the compressed samples and the results were reported.