A new class of magnesium alloys has been developed by dissolving large amounts of oxygen atoms into a magnesium lattice (Mg-O alloys). The oxygen atoms are supplied by decomposing titanium dioxide nanoparticles in a magnesium melt at 720 °C; the titanium is then completely separated out from the magnesium melt after solidification. The dissolved oxygen atoms are located at the octahedral sites of magnesium, which expand the magnesium lattice. These alloys possess ionic and metallic bonding characteristics, providing outstanding mechanical and functional properties. A Mg-O-Al casting alloy made in this fashion shows superior mechanical performance, chemical resistance to corrosion, and thermal conductivity. Furthermore, a similar Mg-O-Zn wrought alloy shows high elongation to failure (>50%) at room temperature, because the alloy plastically deforms with only multiple slips in the sub-micrometer grains (<300 nm) surrounding the larger grains (∼15 1/4m). The metal/non-metal interstitial alloys are expected to open a new paradigm in commercial alloy design.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation (NRF) of Korea (2012-R1A1A-204-2329 and 2013-R1A2A2A-010-68931). H. Choi also acknowledges the support of the NRF of Korea (2009-0093814 and 2013-3005759). Data are available in this manuscript and in the supplementary materials.
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