EVALUATION OF THE MECHANICAL PROPERTIES AND CORROSION BEHAVIOUR OF IRON MODIFIED CU-ZN-AL SHAPE MEMORY ALLOYS

Abstract

The mechanical and corrosion behaviour of iron modified Cu-Zn-Al alloys has been investigated. Cu-Zn-Al alloys containing 20 and 25 wt % Zn was produced by casting method with and without the addition of 0.1wt% iron. The alloys were subjected to a homogenization – cold rolling- annealing treatment schedule, before the alloys were machined to specifications for tensile test, fracture toughness, hardness measurement, corrosion test and microstructural analysis. From the test results, it was observed that the structures of the Cu-Zn-Al alloys were modified by iron addition with near equi-axed grain morphologies developed. There was no significant difference in the hardness of the iron modified and the unmodified Cu-Zn-Al alloys, while the tensile strength, strain to fracture, and fracture toughness of the alloys improved with iron addition. The Cu-Zn-Al alloys also exhibited good corrosion resistance in 3.5wt% NaCl and 0.3M H2SO4 solutions. It was however observed that irrespective of Iron addition, the mechanical properties and corrosion resistance of the Cu-20Zn-4Al-xFe alloy compositions where better in comparison with the Cu-25Zn-4Al-xFe alloy grades (where x=0,0.1 in wt%). Furthermore, the shape memory capacity of the alloys is investigated which show a slight recovery