Creep behaviour of the creep resistant MgY3Nd2Zn1Mn1 alloy

Creep, microstructure and failure of the squeeze cast MgY3Nd2Zn1Mn1 alloy were investigated. The tensile creep tests were performed at 300 degrees C and constant load in the stress range 30-80 MPa. The minimum creep rate epsilon(min), as a function of the stress, follows a power law with the exponent n = 5.9 at 30-70 MPa. The time to fracture t(f) is also a power function of the stress with an exponent m = -4.4. The modified Monkman-Grant relation is valid. Microstructure development during creep exposure of the MgY3Nd2Zn1Mn1 alloy suggests the low stacking fault energy as the main creep controlling factor. The alloy is superior to the WE43 alloy both in time to fracture and in the minimum creep rate about one and two orders of magnitude, respectively. Both the mean value of the modified Monkman-Grant constant and its scatter correspond to the model of constrained growth of cavities along dendrite boundaries. (C) 2007 Elsevier B.V. All rights reserved.