Study on the development of a quaternary layer of B4C-TiB2-Al3Ti-Al in AA7050 / B4C Ex-Situ composite and influence of heat treatment on mechanical and wear properties / Arvind Kumar and Ram Naresh Rai

In the current investigation, AA7050-B4C composite developed through flux
assisted (K2TiF6 flux) stir casting method. The FESEM microstructure studies
confirm the uniform distribution of the reinforcements. The EDAX analysis
confirms the formation of the intermetallic phase of TiB2 and Al3Ti across the
interface of B4C particles and the aluminium matrix. The developed composite
was heat treatment as per T-6 specifications, and a comparative study has been
done on microstructures, mechanical properties and wear properties for ascast
composite(ACC) and Heat-treated composite (HTC). The effect of heat
treatment on the microstructure and bond mechanism shows that the B4C
particles are fairly incorporated in the matrix. Ti decomposes and forms
quaternary layers of B4C-TiB2-Al3Ti-Al across B4C particles. These layers not
only prevent the decomposition of B4C particles into the matrix, also acts as
the effective load transfer layers. Consequently, there is an enhancement in
tensile strength by 16.4%, hardness by 15.9%, compressive strength by 14.8%,
and impact strength by 10.9%. This may be due to the interface strengthening
and precipitation hardening mechanism. There is a significant reduction in
wear rate and coefficient of friction after heat treatment; this may be due to
the improvement in hardness and compressive strength of the composite.