Mechanical properties and microstructure of precipitation-hardened Al-Cu-Zn alloys

Abstract

Many automobile components are made from aluminium and its alloys because of their suitable properties. Metals and their alloys are usually subjected to heat treatment in order to improve their properties. Thus, the effect of precipitation hardening on the mechanical properties and microstructure of sand cast aluminum alloys was investigated. The cast AlCu-Zn alloy samples were heat-treated at 460 °C for 2 hours, quenched in water and then age-hardened at 160 °C for 5 hours. Tensile, impact and hardness tests were carried out on the heat-treated and the as-cast Al-Cu-Zn alloys samples. The surface morphology of both the as-cast and the precipitation hardened samples was observed using digital metallurgical microscope. The ultimate tensile strength of the precipitation hardened samples A2 (81.2Al: 1.56Cu: 8.33Zn) and B2 (81.7Al: 3.25Cu: 6.16Zn) are 173.42 N/mm 2 and 168.02 N/mm 2 , respectively. These values are higher than those of the as-cast samples A1 and B1, which are 168.02 N/mm 2 and 157.84 N/mm 2 , respectively. The precipitation hardened Al alloy samples also displayed higher hardness, impact energy and elongation than the as-cast samples, indicating improved properties. The presence of coarse reinforcing intermetallic phases was observed in the as-cast samples as compared to the well-distributed fine grain size microstructure of intermetallic phases in the precipitation hardened samples. It can be concluded that precipitation hardening improves the mechanical and microstructure properties of aluminum alloys and thus will find wider applications in automobile industries for the production of components and parts.

Influence of mechanical properties on load sequence effect and fatigue life of aluminium alloy

“…Both AA6061 and AA7075 are widely used in applications because of their good mechanical properties, high strength-to-weight ratio, market acceptability, and extensive use in alloy development [21][22][23][24]. Hence, understanding their mechanical properties and fatigue life behaviour can reduce maintenance costs.…”

Tafel Polarization and Impedance Studies of Al-7075 Alloy and Its Composites in Different Medium.

“…The rate of cooling and solidification of ingots plays an important role in the distribution of the ceramic particulates in the ingots and formation of precipitates at intermetallic regions which leads to intense corrosion. The increase in corrosion rate in some composites as shown in Table-4 in HCl and NaCl medium is due to the formation of precipitates like MgO 2 and CuAl 2 which are cathodic to base matrix on reinforcement confirmed from the elemental analysis [9,10,[28][29][30]. In case of hybrid composites slight increase in corrosion rate might be due to galvanic coupling in presence of graphite and also may be due to formation of Al 4 C 3 at the interface during fabrication processing, hydrolysis of Al 4 C 3 on exposure to moisture leads to fissures at graphite base matrix interface which may leads to pitting corrosion.…”

Investigation of micro-structure and mechanical properties of three steel alloys

“…The investigation of microstructure and mechanical properties of stainless steels having 0.004 wt %C to 0.034 wt %C was conducted and the martensitic texture was found to be influenced by carbon content [40]. The hardness and strength of the stainless steel increased by an increase in carbon content but at the same time decreased elongation and toughness [41]. The paper investigated the mechanical properties and microstructural behaviour by precipitation hardening effect on Al-Cu-Zn alloys and found that precipitation hardening increased the mechanical properties of aluminium alloys widely used in automobiles [42].…”