The kinetics of phase transformations during continuous cooling of Ti6Al4V alloy from the diphase α + β range

Abstract

The paper reports on a study of the kinetics of phase transformations during continuous cooling of the diphase Ti6Al4V titanium alloy from the diphase α+β range (950°C). It has been found that within the whole range of applied cooling rates a diffusional β → α transformation occurred. Metallographic observations of the alloy's microstructure gave evidence of changes in the α phase morphology. Upon cooling at between 7.1 and 0.9°C/s the α phase precipitates show lamellar character (Widmannstatten structure), while at the slowest rates (0.23÷0.01 l°C/s) the α phase precipitates in a form of grains. Besides microstructural changes, dilatometric effects were also observed which corroborates occurrence of phase transformations in the alloy.