Superplasticity has been widely used in metals, ceramics and their composites. Metal foams are new materials that offer opportunities in a wide range of industrial applications. They can be used for lightweight structures, biomedical implants, filters, heat exchangers, sound absorbers and mechanical damping devices. Recently, the authors found that superplastic forming allowed the development of metal foams with excellent properties. This talk reviews three examples of metal foams combined with superplastic forming as follows. (i) Superplastic diffusion-bonding in metal foams; Metal foams are often used as a core material of sandwich panels. Bonding of the metal foam with face sheets is quite important for industrial applications. However, conventional welding process cannot be applied on metal foams. Solid-state diffusion-bonding without melting is preferable for metal foams. Superplastic diffusion-bonding process enabled to assist the diffusion-bonding of metal foams with other materials. (ii) Superplastic forming and foaming; Plastic forming of metal foams is difficult due to easy fracture of their cell structure. Therefore, plastic forming and foaming should be carried out simultaneously for near net-shape applications. The authors have succeeded to fabricate the bulge structure with pores using superplastic 5083 aluminum alloy sheets. (iii) Superplastic Zn-22Al alloy foams; Zn-22Al alloy is typical superplastic material with high strain rate sensitivity exponent (m-value). Aluminum foams have been used as an energy absorbing material of automobiles. However, aluminum alloys have small m-value that is not suitable for energy absorption in high speed region. Zn-22Al alloy foams developed by the authors showed large m-value and energy absorption compared to conventional aluminum foams.
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