MATERIAL – Magnesium alloy
Prof Sushanta Kumar Panigrahi of IIT-Madras, along with Dr R S Mishra of the University of North Texas have developed an alloy of Magnesium and some rare earths, which is ultra-light and super strong, and therefore suitable for use in automobile and aerospace industries.
Magnesium is a light metal but its use has been hampered by its qualities such as low strength, strength asymmetry and poor formability. Panigrahi and Mishra have developed “an ultrafine-grained magnesium alloy with extraordinary strength and ductility, zero asymmetry and excellent high strain superplasticity.
They alloyed Magnesium with three rare earths—Gadolinium (Gd), Yttrium (Y) and Zirconium (Zr) [Mg-6Y-7Gd-0.5Zr]. Then they subjected it to three-pass friction stir processing (FSP) and ageing treatment to develop UFG microstructure with hierarchical (fine and coarse) precipitates. First two FSP passes were carried out with high heat input for solutionization and grain refinement. The third FSP pass was carried out with low heat input for texture randomization and further microstructural refinement. The nano-precipitates were dispersed into the UFG matrix by proper aging treatment of 65 h at 180°C to achieve high strength and HSRS.
“We developed a wrought Mg-RE alloy microstructure with negligible tension-compression symmetry, high specific strength, highest combination of strength-ductility and excellent HSRS among all the existing Mg alloys reported in the literature till today,” says Panigrahi.
This processing strategy may be easily adapted to many other rare earth contained Mg alloys to achieve exceptional structural efficiency, he says.
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Please also see High density graphite for crucibles and moulds