Substitution of Zn for Cu in Mg–Y–Zn alloys designed for fracturing ball

The microstructure, mechanical properties and degradation behaviour of Mg 95 Y 3 Zn 2 (MYZ), Mg 95 Y 3 Zn 1 Cu 1 (MYZC), and Mg 95 Y 3 Cu 2 (MYC) (at.-%) alloys have been studied. All the alloys mainly contain α-Mg matrix and LPSO phase. By substituting Zn for Cu, the composition of the LPSO phase transformed from Mg–Y–Zn to Mg–Y–Zn–Cu, and then to Mg–Y–Cu. The ultimate compressive strength is 227, 231 and 238 MPa, respectively. The MYC alloy exhibited much higher degradation rate than MYZC and MYZ alloys. The strong galvanic coupling effect between LPSO phase and the matrix, the grain size refinement and the weak protection from the corrosion product layer are responsible for the high degradation rate. It is suggested that the newly developed MYC alloy is promising for fracturing ball application.