Mechanical properties of Co₃Ti containing boron, carbon and beryllium

Abstract

The mechanical properties of the recrystallized Co₃Ti alloys doped with boron, carbon and beryllium were investigated by tensile testing. The addition of boron significantly improved the strength of the Co₃Ti alloys below the peak temperature of yield stress whereas the addition of carbon or beryllium was not so effective. The yield stresses obtained were evaluated as a sum of three temperature-dependent terms. The addition of boron and beryllium reduced the activation energy for the thermal stress to promote the anomalous positive temperature dependence whereas the addition of carbon enhanced this energy. The addition of boron to Co₃Ti alloys reduced the elongation values at all temperatures while the addition of beryllium increased the values at 700 to 800 K and also at room temperature. The addition of carbon did not affect the elongation values. The fracture patterns correlated well with the levels of elongation, depending on the alloys and testing temperatures. The higher the elongation values, the more fractional area of the transgranular fracture modes increased.