Phase transformation in TC21 alloy during continuous heating

A dilatometry for investigating phase transformation in TC21 alloy was observed at constant heating rate. These experiments were conducted at a computer-controlled horizontal pushrod dilatometer to monitor the thermal expansion caused by the transformation as a function of heating time under different heating rates. Microstructures at different stages of the transformation had been observed by scanning electron microscopy. Results showed that phase transformation in TC21 alloy during continuous heating included three stages, retained β → acicular α, acicular α → β and equiaxed α → β. The rates of the alloy expansion decreased after an increase, and then increased intensively, and finally, it decreased to a constant. Moreover, the activation energy value related to the α → β transformation in TC21 alloy was evaluated based on the JMA equation.