DEVELOPMENT AND CHARACTERIZATION OF Al-Zn BASED COMPOSITE REINFORCED WITH Cu PARTICLES FOR AUTOMOBILE APPLICATIONS

Abstract

The development and characterization of Al-Zn based composites reinforced with Cu particles for potential applications in automobile sector was investigated in this research. Four Al-Zn based compositions: Al-Zn alloy, Al-Zn/6 wt.% Cu, Al-Zn/8 wt.% Cu, and Al-Zn/8 wt.% SiC were produced via double stir casting method. Analytical pure grades of Cu (99.99%) and SiC (97.98%) with average particle sizes of 40 μm and 10 μm, respectively were selected as the reinforcements. Charge calculations were carried out in order to achieve the target composite compositions of 6 wt.% Cu, 8 wt.% Cu and 8 wt.% SiC in the Al-Zn alloy. Structural analyses, mechanical, damping, and corrosion properties were used as basis to characterize the Al-Zn based systems produced. The results show that production of sound Al-Zn composites reinforced with Cu particles was viable, with near absence of dissolved Cu in the Al-Zn matrix, and marginal presence of melt reaction -induced intermetallic phases. Besides hardness, the strength parameters- ultimate tensile strength (149.33 MPa and 138.64 MPa) and specific strength (54.3 MPa.cm3g-1, 51.16 MPa.cm3g-1) of the Al-Zn composites reinforced with 6 wt.% and 8 wt.% Cu, were superior to the unreinforced Al-Zn alloy (103.47 MPa) and the 8 wt.% SiC reinforced composites (130.5 MPa). The fracture toughness (17.32 MPam1/2, 13.66 MPam1/2) and percentage elongation (15%, 12.5%) of the 6 wt.% and 8 wt.% Cu reinforced Al-Zn composites, surpassed that reinforced SiC (K1c- 12.28, MPa m1/2, %Ɛr- 9.5%). The damping properties were generally temperature sensitive, with all compositions exhibiting increase in damping capacity at test temperatures 100-200 ºC. The corrosion susceptibility in 0.3 M H2SO4 was more intense for the 8 wt.%. Cu reinforced composite compared to the other Al-Zn systems investigated. The results established that Al-Zn based composite reinforced 6 wt.% Cu has the best balance of mechanical, damping, corrosion properties for the target applications.