Creep properties and controlled creep mechanism ofas-cast Mg-5Zn-2.5Er alloy
(School of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China)
Abstract: The creep behaviors of as-cast Mg-5Zn-2.5Er alloy (mass fraction, %), under various applied stresses (50−70 MPa) and creep temperatures (150−200 ˚C) for 100 h, were investigated. The stress exponent n is in the range of 1.5−5.8, and the activation energy Qc is in the range of 28.3−77.1 kJ/mol. With respect to the calculated n and Qc as well as the microstructures after creep, it is suggested that there is a transition region between grain boundary sliding(GBS) dominated creep to dislocation creep mechanism (from n<3 to n>3), arising in the steady-stage creep rate value of 2.89×10−9 s−1.
Key words: magnesium alloy; as-cast magnesium alloy; creep mechanism; erbium