Microstructure and mechanical properties of ultrafine grained Mg 97Y 2Zn 1 alloy processed by equal channel angular pressing

Abstract

The Mg 97Y 2Zn 1 alloy processed by equal channel angular pressing (ECAP) has been investigated. It was found that the blocks of secondary phase were broken into uniform distributed sections after ECAP. The Mg 97Y 2Zn 1 alloy processed by ECAP obtained ultrafine grains and exhibits excellent mechanical properties. The average grain size of about 330 nm, yield strength (YS) of 400.3 MPa and ultimate tensile strength (UTS) of 450.0 MPa were obtained by two-step ECAP of 4 passes at 623 K and 2 passes at 603 K. The long-period stacking (LPS) structures contribute to the formation of ultrafine grains in ECAP processed Mg 97Y 2Zn 1 alloy. The results demonstrate that ECAP instead of rapid solidified powder metallurgy (RS/PM) can refine grain size and enhance the strength of Mg 97Y 2Zn 1 alloy. It was also found that the elongation of alloy is decreased with increasing pass number. It was found that cracks were preferentially initiated and propagated in the interior of X-phase during the process of ECAP.