Effect of aging on Zamak 3

Zamak 3 is a zinc-aluminum alloy with a composition of 3.7-4.3 %Al, <0.05 % Cu, 0.02-0.06 % Mg, rest is Zn. It is well suited for pressure die casting and it results in sufficient mechanical properties and a good surface finish. Zamak 3 is utilized in applications automotive industry, household appliances, in structural applications of buildings, etc. It was reported in literature that the mechanical properties of the zamak alloys deteriorate in time at room temperature. In the present study, this effect was investigated by artificial aging of zamak 3 alloy. Zamak 3 samples were produced by cutting and melting of Zamak 3 ingots at 500 oC, and casting into steel molds. Aging experiments were conducted by keeping the Zamak 3 samples in a muffle furnace for 24 h at temperatures of 85 oC, 105 oC and 130 oC. Optical and scanning electron microscopy was employed for investigating the microstructure of the samples. Hardness values of the samples were measured by a Brinell hardness tester. A universal testing machine was used for conduction three point bending tests of the samples. It was found that both hardness and bending strength of Zamak 3 alloy decreased with increasing aging temperature. Hardness and strength values of Zamak 3 were 89 HB10 and 490MPa, respectively. After aging at 130 oC hardness and strength values were found to fall to 75 Brinell 10 and 415 MPa, respectively.