EFFECT OF TIC AND B4C ON MECHANICAL PROPERTIES OF AA7075 ALLOY FABRICATED BY POWDER METALLURGY

Abstract

In this work, aluminum metal matrix composites (AMMCs) were fabricated by using
powder metallurgy. AA7075 powder is reinforced with two different ceramic particles
(TiC,B4C) with different weight fractions (2.5, 5, 7.5 and 10 wt.%). The composites were
produced by powder metallurgy by preparing the powder, mixing, compacting and
sintering. The particle size of unreinforced AA7075 about 100?m, while particle size of
each TiC and B4C about 150 ?m. The mixing process was done by planetary mixing setup
rotating at 250 rpm for 2hr. by adding zinc stearate as an activator material with steel ball
milling. However the mixture was compacted by hydraulic uniaxial press type (Leybold
Harris No.36110) about 200 kg/cm² according to (ASTM-D 618). After compacting
process, the mixture sintered at 475 °C for 2hr. by using electrical furnace with argon
atmosphere.
There are many examinations and tests were carried out for the synthesized composites
material (AA7075/ TiC and AA7075/ B4C) such as examination of the microstructure,
mechanical tests such as hardness and compressive strength, physical tests such as
density and porosity.
The results of this work showed that improving in physical properties (theoretical
density, experimental density, porosity) and mechanical properties (Rockwell hardness
and Compressive strength)