Microstructure and Mechanical Properties of Vacuum Hot Pressed P/M Short Steel Fiber Reinforced Aluminum Matrix Composites

Abstract

Commercial purity aluminum powder of irregular shape and ligamental morphology having average particle size of 75 µ m was blended with medium carbon steel short fibers having average diameter of 100 µ m and maximum length up to 1000 µ m. The green compacts of pure aluminum and reinforced compositions were hot-pressed in 10 −3 torr vacuum, at 723 K, 773 K, and 823 K for 5, 10, and 15 min durations under 50 MPa axial stress on Gleeble 3800 simulator. Microstructures of the sintered composites have been studied by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). The sintered compacts were characterized for densification behavior, hardness, and growth of Fe x Al y reaction interface. Positive densification parameter was achieved for up to 10 wt.% reinforcement fraction. The maximum hardness of 51 Hv was achieved for 10 wt.% at 823 K for 15 min sintering time. The reaction interface was analysed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). The reaction interface was found to be composed of Fe 3 Al, FeAl 2 , Fe 2 Al, Fe 3 Al, Fe 4 Al, Fe 2 Al 5 , and FeAl intermetallics. Growth of the reaction interface was diffusion-controlled which followed a nearly parabolic law with a rate constant of 1.41 × 10 −12 m 2 s −1 at 823 K.