Effect of Vacancies on the Tensile Properties of Fe-40Al Single Crystals in Air and Vacuum

Tensile tests in both air and vacuum have been performed on Fe-40Al single crystals containing two different vacancy concentrations. It is shown that the room temperature fracture strengths are significantly increased but the elongations are decreased in both test environments at high vacancy concentration. The fracture mechanisms are controlled by the vacancy concentration, with vacancies promoting the fracture along the slip planes.