Effects of rare-earth elements on the glass-forming ability and mechanical properties of Cu46Zr47-xAl7Mx (M = Ce, Pr, Tb, and Gd) bulk metallic glasses

Cu46Zr47-xAl7Mx (M = Ce, Pr, Tb, and Gd) bulk metallic glassy (BMG) alloys were prepared by copper-mold vacuum suction casting. The effects of rare-earth elements on the glass-forming ability (GFA), thermal stability, and mechanical properties of Cu46Zn47-xAl7Mx were investigated. The GFA of Cu46Zr47-xAl7Mx(M = Ce, Pr) alloys is dependent on the content of Ce and Pr, and the optimal content is 4 at.%. Cu46Zr47-xAl7Tbx (x = 2, 4, and 5) amorphous alloys with a diameter of 5 mm can be prepared. The GFA of Cu46Zn47-xAl7Gdx(x = 2, 4, and 5) increases with increasing Gd. T-x and T-p of all decrease. T-g is dependent on the rare-earth element and its content. Delta T-x for most of these alloys decreases except the Cu46Zr42Al7Gd5 alloy. The activation energies Delta E-g, Delta E-x, and Delta E-p for the Cu46Zr42Al7Gd5 BMG alloy with Kissinger equations are 340.7, 211.3, and 211.3 kJ/mol, respectively. These values with Ozawa equations are 334.8, 210.3, and 210.3 kJ/mol, respectively. The Cu46Zr45Al7Tb2 alloy presents the highest microhardness, Hv 590, while the Cu46Zr43Al7Pr4 alloy presents the least, Hv 479. The compressive strength (sigma(c.f.)) of the Cu(46)Zr(43)Al(7)Gd(4)BMG alloy is higher than that of the Cu46Zr43Al7Tb4 BMG alloy.