This paper is concerned with the existence of a global attractor for a semi-flow governed by the weak solutions to a nonlinear one-dimensional thermoviscoelastic system with clamped boundary conditions in shape memory alloys. The constitutive assumptions for the Helmholtz free energy include the model for the study of martensitic phase transitions in shape memory alloys. To describe physically phase transitions between different configurations of crystal lattices, we work in a framework in which the strain u belongs to L∞. New approaches are introduced and more delicate estimates are derived to establish the crucial L∞ -estimate of strain u in the course of showing the compactness of the orbit of the semi-flow and existence of an absorbing set.