Superplastic micro-forming of microstructures

Superplastic micro-forming processes have been applied to forming and fabrication of micromechanical components. Selected materials are a fine grained superplastic Al-78Zn alloy, pure iron as a transformation superplastic material, and amorphous LaAlNi, ZrAlCu alloys which exhibit a supercooled liquid state. With these materials, microformability tests have been carried out with the specially developed evaluation system by using V-grooved micro dies made of (100)silicon. The throat width of the V-groove is from 1 to 20 μm. With these dies, micro-forging has been carried out and the characteristics of micro-formability of the material have been clarified. In a fine grained superplastic alloy of polycrystalline aggregates, the accuracy limit of micro-formability is depend on the grain diameter. On the other hand, quite superior formability has been observed in the amorphous alloys after forming under a supercooled liquid condition. These results indicate an importance of a deformation mechanism from a view point of polycrystalline structure or a micro(μm) scopic scale. A good micro-formability shown above has been applied to a closed die forging of microstructures such as micro pyramids and microdouble gear system. As a result, superplastic materials and amorphous alloys are useful for micro-forming and fabrication of microstructures or components for MEMS.