Advantages of hot compression in the manufacture of Al-B4C composites

Abstract

The aim of this work was to prove that preparation of Al-B₄C by hot compression at 350 °C (HC) followed by sintering at 550 °C would improve mechanical properties with respect to manufacturing by cold compression (CC) followed by sintering at the same temperature, the later experiments were carried out in a previous work. Samples with aluminum matrix adding 0, 3, 5 and 7% were prepared by powder metallurgy technique and tested. The mechanical properties were better using HC. Remarkably, resistance to compression was 3.5 times larger for HC. Vickers hardness, resistance to wearing and impact, as well as density were higher for HC. Scanning electron microscopy of CC specimens exhibit a cellular microstructure while HC ones display a smooth appearance. The better properties of the HC samples are explained due to an improved flow of material at higher temperatures of compression.