Effect of Cu and Ni on the mechanical properties and fracture behavior
of Al–Si–Mg cast alloys
Chem.
Met. Alloys 7 (2014) 154-159
https://doi.org/10.30970/cma7.0281
Abul HOSSAIN, A.S.W. KURNY
The effect of addition of Cu or Ni on the
microstructure and mechanical properties of an
Al-6Si-0.5Mg alloy was investigated. The alloys were cast into pre-heated metal
moulds, homogenized (24 h at 500°C), solution-treated (2 h at 540°C)
and aged for 1 h at temperatures of up to 300°C; the age-hardening stages
were monitored by hardness measurements. Tensile properties of the aged alloys
were evaluated at nominal strain rates of 10-3 s-1. The
yield strength and fracture strength of the alloys were found to increase with
increasing ageing temperature and to be maximum in the peak-aged condition
(1 h at 225°C), whereas the ductility and impact toughness decreased with
increasing ageing temperature. The addition of 2 wt.%
Cu to the Al-6Si-0.5Mg alloy resulted in an increase of the hardness and
tensile strength and substantial reduction of the ductility and fracture
toughness. The fracture toughness of the Al-6Si-0.5Mg-2Ni alloy, containing
2 wt.% Ni, was lower for all ageing treatments
and lowest at the peak-aged condition. SEM fractographs of broken specimens showed both ductile and
ductile-brittle fracture behavior.
Microstructure of a solution-treated
Al-6Si-0.5Mg cast alloy (Alloy-1)
Keywords
Al-6Si-0.5Mg
alloy / Microstructure / Tensile strength / Fractograph