Creep mechanism of as-cast Mg-6Al-6Nd alloy

Abstract

The creep mechanism of as-cast Mg-6Al-6Nd alloy was studied. The stress exponent for creep is 5.8 under the applied stresses of 50–70 MPa at 175°C. The activation energy for creep is 189 kJ·mol−1 under the applied stress of 70 MPa in the range of 150–200°C. The true stress exponent and threshold stress for creep are calculated as 4.96 and 10.2 MPa, respectively. The true stress exponent indicates that its creep mechanism belongs to the dislocation climb-controlled creep, which is in agreement with the microstructure changes before and after creep. The high value for stress exponent is attributed to the interaction of Al11Nd3 phase with dislocations. The activation energy is more than the self-diffusion activation energy of Mg, which is attributed to the load transfer taking place from the matrix to Al11Nd3 phase during creep.