Environmental effects on the mechanical properties of Co3Ti containing boron,carbon and beryllium

The environmental effects on Co₃Ti polycrystals doped with boron, carbon and beryllium were investigated by tensile testing in air at 293 to 1173 K and the results were compared with those tested in vacuum. The yield stresses of the alloys observed were independent of the test environment. The elongation and ultimate tensile strength of the alloys observed were strongly dependent on the test environment and also the test temperatures. Ductility losses were found for the samples which were tested in air at temperatures below 473 K. The losses were accompanied by a change in fracture mode from transgranular to intergranular. It was suggested that this embrittlement was due to the hydrogen absorbed from air. Neither species boron, carbon nor beryllium were observed in this work to affect the environmental effects on the ductility behaviour of Co₃Ti alloys.