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MA: Fachverband Magnetismus

MA 56: Bulk Materials: Soft and hard permanent magnets

MA 56.6: Vortrag

Donnerstag, 23. März 2017, 16:15–16:30, HSZ 403

Producing two different L1₀ phases in ternary MnAlGa alloys — •Torsten Mix^1,2, Florian Bittner^1,3, Karl-Hartmut Müller¹, Ludwig Schultz^1,2,3, and Thomas George Woodcock¹ — ¹IFW Dresden, Institute for Metallic Materials, PO Box 270116, 01171 Dresden, Germany — ²Department of Physics, TU Dresden, Dresden, Germany — ³Institute for Materials Science, TU Dresden, Dresden, Germany

The L1₀ phases in the binary MnAl and MnGa systems are interesting candidates for rare earth free permanent magnets. The main drawbacks, are the high price of Ga and the poor resistance to decomposition at evelated temperature of the metastable L1₀ phase in binary MnAl. As the L1₀ phase in MnGa is thermodynamically stable, the formation of a ternary MnAlGa alloy is a promising approach to overcome these difficulties. Ternary alloys of the form Mn₅₅Al_45−xGa_x have been produced in the range 0 < x < 45. In alloys with 5 < x ≤ 9 after appropriate heat treatments, two different phases with the L1₀ structure can be made to coexist. One is stable as in the binary MnGa system, the other metastable as in binary MnAl. The magnetic properties of the ternary alloys are superior to those of the binary analogues. The thermal stability of the metastable phase is greatly improved by the addition of the small amount of Ga. Up to 700^∘C, the decomposition of the metastable phase is strongly suppressed. This allows longer processing time at higher temperatures, thus enabling new routes to produce rare earth free MnAl-based magnets to be envisaged.