Akademik Veri Yönetim Sistemi
MATERIALS TODAY COMMUNICATIONS, cilt.30, sa.5, ss.1-14, 2022 (SCI-Expanded)
In this study, Al-Si compacts and Al-Si/B4C composites were produced from hypereutectic Al-Si alloy powders by
cold pressing/conventional sintering and cold pressing/microwave sintering techniques. The effects of sintering
temperature, sintering time and B4C particle addition on microstructural properties, density, hardness and
transverse rupture strength were investigated. The phases and intermetallic compounds formed in the micro-
structure were determined by X-ray diffraction. Densities of the samples were measured by Archimedes’ tech-
nique. Macro hardness measurements were carried out with Brinell hardness test. Three-point bending tests were
applied to the samples according to ASTM-B528–16. Elemental Al regions, master alloy (Al-Si-Cu-Mg) regions,
primary Si particles and Cu- and Mg-rich secondary phases were determined in the microstructure. It was
determined that the Cu- and Mg-rich secondary phases are θ(CuAl2), β(Mg2Si), γ(Al2CuMg) phases. An increase
in porosity was determined in conventional sintered samples compared to green Al-Si specimens. In addition, it
was observed that the amount of porosity increases, grain size and primary Si grains coarse with increasing
sintering temperature in conventional sintering. The change in the amount of pores of the samples produced by
microwave sintering without holding time at the sintering temperature is not as obvious as in conventional
sintering. Similar microstructures were obtained in the samples at increasing sintering temperatures in micro-
wave sintering. In the samples produced by conventional sintering, the hardness value decreased with increasing
sintering temperature. Addition of 5 wt% B4C caused an increase in hardness at all sintering temperatures. The
addition of 10 and 15 wt% B4C caused a decrease in hardness. In microwave sintering, the general trend in
hardness change was a decrease with increasing B4C particle addition and increasing sintering time. Transverse
rupture strength values close to and similar to each other in conventional sintered samples were obtained at
different sintering temperatures. Transverse rupture strength values increased with the addition of 5 wt% B4C
particles, and decreased with the addition of 10 and 15 wt% B4C particles.