Influence of aging time on mechanical properties and microstructures of FeNiAlTa shape memory alloy

Abstract

This paper focuses on the Fe59.5Ni28Al11.5Ta1 memory alloy, in which the effects of different aging treatments on microstructure and properties of the rolled alloy are investigated by metallurgical microscope, X-ray diffraction, SEM, EDS and pressure test machine. Results show that, because of aging treatment, precipitation of γ’ and β’ phase strengthens the austenitic matrix. With the increase of aging time at 600 ℃, the comprehensive analysis of pseudoelasticity curve, shows that the stress-induced martensite critical stress of the aging state of the alloy decreases first and then increases; the alloy compressive strength, the recoverable strain and the hardness increase first and then decrease, Besides, the alloy residual strain is first decreased and then increased. When the aging time is 60 h, the alloy compressive strength is the maximum, up to 1306 MPa, the alloy recoverable deformation is the maximum, reaching 14.9%, the hardness of the alloy is also the largest, but the alloy residual strain is relative minimum. With the increase of aging time, alloy maximum strain decreases gradually, and the plasticity of the alloy also decreases gradually. The properties of the shape memory alloy are influenced by the particle size, its distribution, volume fraction, of precipitate phase etc.