Study on Hot Deformation Behavior and Microstructure Evolution of Different Energy Dissipation Regions of 54Ni46Ti Alloy

Abstract

The characteristics of energy and microstructure 54Ni46Ti alloy are studied by hot compression simulation test, XRD, EBSD, and TEM observation. The unstable interval and the optimum processing parameters are accurately predicted by constructing the hot processing map. In this study, the energy analysis of the hot deformation process was realized by combining the power dissipation rate and the microstructure characteristics. As a result, the 54Ni46Ti alloy has a temperature-unstable region, a high-temperature unstable region, and a suitable processing region under the experimental parameters. In the unstable region, the unstable crack appears due to the high dislocation density inside the alloy structure. The average dislocation density of the alloy in unstable different areas is 4.633×1014m-2 and 2.879×1014m-2, and the dynamic recrystallization (DRX) content is 3.9% and 48.1%, respectively. In the suitable processing region, the η value is higher. Under the conditions of 850°C and 0.01s-1, the DRX fraction of the alloy is 50.4%, and the average dislocation density is 1.397×1014m-2. At 900°C, 0.01s-1, the DRX fraction is 59.6%, and the average dislocation density is 0.841×1014m-2. In the suitable processing region, the softening mechanism is DRX.

Keywords: NiTi, Isothermal compression, Microstructure, Processing map