Structural analysis, mechanical and damping behaviour of Al-Zn based composites reinforced with Cu and SiC particles

Abstract

The structural characteristics, mechanical and damping properties of stir-cast Al-10 wt.% Zn based composites developed using 6 and 8 wt.% Cu, and 8 wt.% SiC particles as reinforcements, were investigated. The low porosity (<4%), near absence of dissolved Cu in the Al-Zn matrix, and marginal presence of melt reaction-induced intermetallic phases, attest to the soundness of the castings. Besides hardness, the strength parameters − ultimate tensile strength (149.33 MPa and 138.64 MPa) and specific strength (54.3 MPa cm3 g−1 and 51.16 MPa cm3 g−1) − of the Al-Zn composites reinforced with 6 and 8 wt.% Cu, were superior to that of the unreinforced Al-Zn alloy (103.47 MPa) and the 8 wt.% SiC reinforced composite (130.5 MPa). The fracture toughness (17.32 MPa m1/2 and 13.66 MPa m1/2) and percentage elongation (15% and 12.5%) of the 6 and 8 wt.% Cu reinforced Al-Zn composites, also surpassed that reinforced with SiC (KIC − 12.28 MPa m1/2; % εf − 9.5%). Improved matrix/particles interphase bonding and the inherent ductile and tough nature of Cu over SiC, were cited responsible for the improved strength-ductility-toughness balance of the Al-Zn/Cu composites over that reinforced with SiC. The damping properties were generally temperature sensitive, with all compositions exhibiting increase in damping capacity at test temperatures 100–200 °C.

Dynamic mechanical damping analysis of up/step-quenched Cu-Zn-Sn-based shape memory alloys

“…The ratio of energy dissipated by heat per cycle to mechanical energy absorbed or stored in the material subjected to stress is known as the damping capacity (tan δ) of the material [42]. Damping capacity (tan δ) in terms of the energy loss in the material due to viscous friction is determined mathematically using the relation in equation (1) [43]:…”