Texture and Microstructure of Meltspun Shape Memory Alloys

Abstract

Shape memory effects are based on the shear stress sensitivity of the orientation of lattice variant and invariant shear which is associated with reversible martensitic phase transformation. The effect of texture and microstructure of the high temperature phase was investigated with copper based shape memory alloys. Rapid solidification can produce either a columnar grain structure with a pronounced 〈100〉 fibre texture, or an equiaxal structure with a grain orientation close to random. It could be shown that the columnar and textured grain structure produces the maximum shape memory effect in β ‐Cu alloys if the ribbon shaped specimen is exposed to tensile stress parallel to the length of the ribbons. These effects are explained by the influence of primary texture of the high temperature phase on the texture which originates in the martensitic low temperature phase if the transformation occurs under an external load.