Grain boundary characteristics and tensile properties of Ti14 alloy after semi-solid deformation

Abstract

The microstructure and room-temperature tensile properties of Ti14, a new α+Ti₂Cu alloy, were investigated after conventional forging at 950°C and semi-solid forging at 1000 and 1050°C, respectively. Results show that coarse grains and grain boundaries are obtained in the semi-solid alloys. The coarse grain boundaries are attributed to Ti₂Cu phase precipitations occurred on the grain boundaries during the solidification. It is found that more Ti₂Cu phase precipitates on the grain boundaries at a higher semi-solid forging temperature, which forms precipitated zones and coarsens the grain boundaries. Tensile tests exhibit high strength and low ductility for the semi-solid forged alloys, especially after forging at 1000°C. Fracture analysis reveals the evidence of ductile failure mechanisms for the conventional forged alloy and cleavage fracture mechanisms for the alloy after semi-solid forging at 1050°C.

Keywords

titanium alloys / semi-solid forging / grain boundaries / tensile properties / fracture

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