Effect of Foaming Condition on Cell Morphology of Superplastic Zn-22Al Alloy Foams Manufactured through Melt Foaming Process

Closed-cell superplastic Zn-22Al eutectoid alloy foams were manufactured through the melt foaming process using titanium hydride powder as a foaming agent. Foaming tests were carried out under different foaming temperatures, times and additive amounts of foaming agent. Maximum porosity of 75% and small pore diameter were obtained during the temperature range of semi-solid condition from 738-753 K. This is because of increased melt viscosity. Though the small amount of the foaming agent is effective to decrease the pore diameter, the porosity becomes low. Cell morphology of the present Zn-22Al alloy foam is identical to conventional aluminum foams. Semi-solid condition of Zn-22Al foam has an advantage over increasing melt viscosity on manufacturing of metal foam.