The invention produces superplastic deformation in a workpiece by altering the chemical composition of the workpiece material, while the workpiece is subjected to a biasing stress, in a manner that introduces a strain increment into the material that effects a change in a overall dimension of the workpiece without causing failure. In one approach, repeated cyclic alteration of chemical composition, so as to repeatedly alternately induce and reverse a phase transition that produces strain increment, allows accumulation of strain in an incremental fashion thereby achieving large overall superplastic deformations in the workpiece without applying large stresses.
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