Metallic glass layers produced by high power lasers

The concepts surrounding glassy metallic alloys have been directed towards the production of thick (= 250 μm) amorphous surface layers on light metals such as aluminium and titanium, by harnessing the processing power of high power Nd:YAG lasers to achieve the inherently high cooling rates required to form many of today's bulk metallic glasses. Microstructural and chemical observation techniques include secondary electron microscopy (with EDS), transmission electron microscopy (with EDS), and X-ray diffraction, which reveal fully amorphous layers are attainable. Coating to substrate adherence is achieved by virtue of a functionally graded, often amorphous matrix, interlayer around 50 μm in depth. Thermo-dependant properties have been explored by differential scanning calorimetry and in-situ heating with transmission electron microscopy. Hardness and nano -indentation profiles reveal hardnesses up to 13 GPa over the full depth of a coating, coupled with elastic modulus around 150 GPa. Tribological tests have also been conducted and possible applications explored.