Microstructure characterisation and mechanical properties of rapidly solidified Mg–Zn–Ca alloys with Ce addition

AbstractThe rapidly solidified (RS) Mg–Zn–Ca based alloys with Ce addition were produced via atomising the alloy melt and subsequently splat quenching the atomised droplets on the water cooled copper twin rollers in the form of flakes. The alloys were characterised by XRD, SEM, HRTEM, DSC and microhardness. All the alloys are characteristic of fine grains in the size of 1–5 μm. The RS Mg–6Zn–5Ca ternary alloy is composed of α–Mg, Mg2Ca, Ca2Mg6Zn3 and a small quantity of Mg51Zn20, Mg2Zn3 and MgZn2. With the increment of Ce, the Mg12Ce phase in the alloy increases and the Mg51Zn20, Mg2Zn3 and Ca2Mg6Zn3 phases decrease, seemly indicating that the proper Ce content is beneficial to the suppression of the latter phases. Moreover, the addition of Ce to the Mg–Zn–Ca alloy contributes to the enhanced thermal stability of the phases in the alloys, especially for the Mg–6Zn–5Ca–3Ce alloy. The microhardness of the RS alloys increases with the increment of Ce, and the strengthening mechanism is discussed.