Superplasticity for Lightweight Metal Foams

Potential applications of superplasticity for lightweight metal foams are reviewed in this paper. Metal foams have been used for lightweight structures, biomedical implants, filters, heat exchangers, sound absorbers and mechanical damping devices. Superplasticity has advantages on metal foaming process and mechanical properties of metal foams. Four examples of metal foams combined with superplastic forming are presented; (i) Enhanced foaming under internal stress superplastic condition, (ii) Superplastic diffusion-bonding of metal foams, (iii) Superplastic forming and foaming and (iv) Superplastic Zn-22Al alloy foam for energy absorbing material.

Application of Superplastic Flow to Manufacturing of Microcellular Aluminum Foams

A new application of superplasticity was proposed in the manufacturing process of metal foams. Preform sheets were manufactured using superplastic 5083 aluminum alloy sheets through accumulative roll-bonding (ARB) process. Microcellular aluminum foam plates with 50% porosity were produced through solid-state foaming under the superplastic condition. The cell shape was oblate spheroid, which is effective to reduce the thermal conductivity. The present aluminum foam plates have a potential as an excellent heat insulator.

On the Extrusion in Superplastic Conditions

In this paper the range within which the slab method is accurate enough to calculate the extrusion pressure in superplastic condition has been determined. A realistic velocity field, supported by experimental evidence, has been adopted. A strain rate field has been evaluated and an appropriate constitutive equation has been introduced. The slab method and the upper bound approach, here developed, have then been used to study the superplastic extrusion through a conical die. A comparison of the two solutions thus obtained has been carried out. It has been found that in any case the curves obtained using the slab method run higher than those obtained using the upper-bound approach. The analysis developed may be used to determine the range within the slab method is accurate enough for engineering purposes.