Creep of a heat treated Mg-4Y-3RE alloy

Creep of WE43-T6 was characterized at temperatures ranging from 423 to 523 K and stresses ranging from to 30 to 300 MPa. Creep stress exponent as well as activation energy were measured. There appears to be a softening in creep strength at temperatures above 473 K, Also, the applied stress level affects the creep mechanism. Microstructures of the alloy both before and after creep were examined. Two kinds of precipitates, metastable beta ' and stable beta phases, were observed in the microstructure. These precipitates readily transform and coarsen during creep. Dislocation-precipitate interaction was quite extensive. Fracture surface revealed that there is a gradual transition from brittle to ductile mode as testing temperature increases. A comparison of the creep properties among the present alloy and other rare earth-containing alloys were made. (C) 2001 Elsevier Science B.V. All rights reserved.