Influence of Thermal-Mechanical Process on the Shape Memory Effect of CuAl9Fe4Ni2 Alloys

Abstract

In recent years, the CuAl9Fe4Ni2 alloy has been studied and applied in the manufacturing. In recent years, scientists have initially found and demonstrated about shape memory effect of this alloy. In addition to increasing, the martensite transformation has increased the strength of the alloy, also creates a shape memory effect by reversing the crystal structure in the aluminum-copper alloy which added nickel, zinc, or iron elements. Martensite can easily be formed when the amount of deformation is about 8%. The crystalline structure of martensite can be monoclinic or orthorhombic. In this paper, we present the research results about the phase transformation process of CuAl9Fe4Ni2 alloy when mechanical-heat-treatment to increase the shape memory effect of this alloy. The research results show that: This alloy is heated at 900 °C to create a martensite phase with large grain size; hot rolling at 800 °C to facilitate the process of shape memory effect. Then, this alloy continued quenching for a second time at 900 °C to create martensite with small grain size and a convenient distribution for the shape memory effect. Continue to conduct cold deformation to energize the martensite sheets, forming the detwinner martensite to facilitate the shape memory effect. Then proceed to reheat at 570 °C to form the process of reversing the martensite phase back to the initial state of the alloy created (α + γ2). SEM analysis proved the existence of the martensite phase β' which has hcp structure with Cu3Al formula is the same as the phase β which has bcc structure but exists in alloys at room temperature (martensite after quenching, residual martensite after tempering and after shape memory effect).