Study On The Microstructure Of Ti-7Cu Alloy After Semi-Solid Foring

Since the proposal of semi-solid processing technology, semi-solid processing technology has become one of the most attractive topics. Fruitful researches on semi-solid processing behavior of both aluminum and magnesium alloys have been carried out and play an important role on the microstructure during semi-solid processing. However, the semi-solid processing behavior of titanium alloys, has not been report. In order to consummate the technology of semi-solid processing in titaniume alloys, the microstructural evolution in the different semi-solid conditions should be studied, firstly.The objectives of this work are to comprehensively investigate the Ti-7Cu alloy, Compression specimens in the semi-solid state with Gleeble-3500 thermal simulation compressor. The main results show that: the semi-solid temperature, strain rate and deformation have a greater impact on the tissue morphology, it is typical eutectoid α + Ti2 Cu tissue in different semi-solid temperatures compression, due to the copper is rapid eutectoid elements, therefore, has not β phase exists at room temperature; With the increase of temperature alloy semi-solid compression, the grains grow significantly. The main reason is the increasing liquid content, thermal activation energy increases, leading to grain grew up. With increasing strain rate, the grain tends to decrease, mainly not enough time to supply the grain combined and growth. With the amount of deformation increasing, the grain size is small obviously, while under the influence of the liquid phase, the grain size becomes uniform.This phenomenon is related to the liquid and stress.During deformation segregation behavior showed that: under cooling conditions will occur eutectoid reaction and peritectic transformation reaction leading to tissue is ɑ-Ti and Ti2 Cu phase after cooled. Grain boundary phase segregation leads to the Ti2 Cu phase segregation in the grain boundary. Segregation of liquid phases and Ti2 Cu phases are associated with deformation temperature. As the temperature increases, Ti2 Cu phase significantly increases in grain boundary. during solidification the needles Ti2 Cu precipitated and grain boundary generated segregation band.