Role of powder preparation route on microstructure and mechanical properties of Al-TiB2 composites fabricated by accumulative roll bonding (ARB)

Accumulative roll bonding (ARB) was conducted up to seven cycles to fabricate Al TiB2 particulate metal matrix composites. The reinforcing particles were prepared and used in three different processing conditions: as-received TiB2, mixed TiB2-Al and in-situ synthesized TiB2-Al. The mixed TiB2-Al powder was produced by milling of TiB2 with Al powder and in-situ synthesized TiB2-Al powder was prepared by mechanical alloying (MA) through inducing TiB2 particles in the Al with various composition of 10, 20 and 30 wt% Al. Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to evaluate the microstructure of the produced composites. The composite obtained from the in situ TiB2-Al powder showed the most uniform distribution of particles and exhibited the highest tensile strength of about 177 MPa in comparison with the composites reinforced with the as-received TiB2 (156 MPa) and mixed TiB2-Al powder (160 MPa). After seven ARB cycles, an. ultra-fine grained structure with the average size of about 300 nm was obtained in the composite reinforced with in-situ TiB2-Al powder. The appearance of dimples in tensile fracture surfaces revealed a ductile-type fracture in the produced composites. (C) 2016 Elsevier B.V. All rights reserved.