Measurement of Thermal Expansion Coefficient of 18R-Synchronized Long-Period Stacking Ordered Magnesium Alloy

We measured the thermal expansion coefficients of an 18R-synchronized long-period stacking ordered magnesium alloy (Mg85Zn6Y9) and an a-phase pure magnesium (alpha-Mg). This was achieved by using a Gandolfi camera, which was attached on a high precision diffractometer at SPring-8 BL40XU beamline. By using this system, fine powder diffraction data could be obtained even from a highly oriented Mg85Zn6Y9 polycrystal at different temperatures between 95 and 440 K. The thermal expansion coefficient along a- and c-axes were determined from the refined cell parameters. The thermal expansion coefficient of the Mg85Zn6Y9 are smaller than those of the alpha-Mg.