US 7,540,899 B1 · Shape memory alloy thin film, method of fabrication, and articles of manufacture

Abstract

A method of forming a single crystal in a thin film by progressively rapidly heating (and cooling) a narrow band of amorphous material. The amorphous thin film may be of shape memory alloy such as TiNi or CuAlNi. Heating may be accomplished by a line-focused laser beam. The thin film may be formed by sputter deposition on a substrate such as silicon. The thin film crystal that is formed has non-isotropic stress/strain characteristics, and very large recoverable strain in a preferred direction. The single crystal SMA exhibits greater strain recovery; Constant force deflection; Wider transition temperature range; Very narrow loading hysteresis; and Recovery that is repeatable & complete. Single Crystal SMA is manufactured by pulling a single crystal from melt, a method similar to that used by the semiconductor industry to fabricate silicon boules. This process enables manufacture of materials that approach theoretical limits.

Claims13

Dependent claims

A method for making a single crystal shape memory alloy thin film comprising the steps of:

depositing a thin film layer of amorphous shape memory alloy material on a substrate;
applying a strip of heat to the amorphous shape memory alloy material to form a crystallization front along the strip;
moving the strip of heat across the amorphous shape memory alloy material in a direction to move the crystallization front across the material;
crystallizing the amorphous material into crystallized material having a single crystal crystallographic orientation;
and
cooling the crystallized material with a heat sink.

3 more elements

Dependencies are inferred from the claim text.

Shape memory alloy thin film, method of fabrication, and articles of manufacture

Life of this patent

Shape memory alloy thin film, method of fabrication, and articles of manufacture

Life of this patent

Abstract

Claims13