Effect of Pulsed Magnetic Field on Precipitation Behavior and Mechanical Properties of TC4 Titanium Alloy

Abstract:

In order to investigate the effect of pulsed magnetic field on precipitation behavior of as-rolled TC4 titanium alloy, a pulsed magnetic field was applied during aging.The effects of electromagnetic energy on microstructure, strength and plasticity of TC4 during aging were studied by SEM,TEM and tensile testing machine.Observation and analysis were carried out at nucleation stage and growth stage respectively.The mechanism of electromagnetic energy in aging process was analyzed by using classical nucleation theory and the first law of diffusion. The results show that the precipitation rate of TC4 is significantly increased due to the addition of electromagnetic energy. The aging time is reduced on the premise of ensuring the mechanical properties. Compared with 4 h without pulse magnetic field, the plasticity of 2 h with pulse magnetic field is increased by 22.67%, and the tensile strength is approximately the same. The aging process under the coupling of pulse magnetic field and temperature field can lead TC4 to over aging stage (2h). In the aspect of tensile fracture, the fracture morphology of fracture is dimple fracture before applying pulse magnetic field 2 hours ago, but when the time increases to 2h, the fracture surface gradually changes to the fracture morphology in quasi solution.The results reveal that the secondary phase precipitation and growth of TC4 can be promoted by pulsed magnetic field through electromagnetic energy, which is due to the synergistic effect of reducing critical nucleation work and promoting atomic diffusion. Overall, electromagnetic energy can promote the precipitation of secondary phase and reduce the aging time.

Key words:TC4 titanium alloy; Pulsed magnetic field; Mechanical properties; Precipitation behavior