Microstructure characterization, mechanical properties, compressibility and sintering behavior of Al-B4C nanocomposite powders

Abstract

In the present work, Al-xB4C nanocomposite (x=0, 1, 2, 3, 4 and 5 in wt%, having the average B4C size of 50nm) were prepared using a high-energy ball mill. The milling times up to 16h were applied. Then, the microstructural evolutions, mechanical properties, compressibility and sintering behavior of nanocomposites were investigated. The changes in powders morphology and microstructure during the milling process were characterized by laser diffraction particle size analyzer (LDA), SEM, XRD, EDS and TEM techniques. Compressibility and sintering behavior of milled powders compacted under different pressures (100–900MPa) and at different sintering temperatures (500, 550 and 600°C) were also studied. The pressing behavior of the nanocomposites was analyzed using linear compaction equations developed by Heckel, Panelli-Filho and Ge. The results showed the significant effects of B4C amounts and sintering temperatures on the compressibility and sintering behavior of nanocomposites. The increase in the B4C amount led to a decrease in both the compressibility rate and the sinterability of specimens. The maximum compression strength of 265MPa and Vickers hardness of 165VHN were obtained for Al-5wt.% B4C nanocomposite milled for 16h followed by sintering at 600°C.