Development of High Strength Cu Alloys of Heusler Matrix with good Workability and Ductility

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The Cu_2MnAl Heuser alloy which is well known as magnetic material is very brittle and had not been fabricated by conventional rolling. In this work, we have tried to enhance the strength, ductility and hot workability of the Cu-Mn-Al alloys by microstructural control based on information of phase diagrams.(1)Phase equilibria in Cu-Mn-Al system : Phase equilibria among alpha, beta and gamma phases at 500。C, 600。C, 700。C and 800。C were determined. It was clarified that addition of Mn stabilizes the beta phase.(2)Order-disorder transition in the beta phase : A2<greater than or equal>B2<greater than or equal>L2_1 order-disorder transition temperatures (Tc) were measured by DSC.The Tc strongly depends on(3)Mechanical properties : The Cu-Mn-Al Heuser alloys with non-stoichiometric composition is very ductile and strong, while that at the stoichiometry is brittle. In the non-stoichiometric region, it was shown that the alloys have good mechanical properties with elongation of (3-21)%, 0.2% proof strength in the region of (500-700)MPa and tensile strength in the region of (700-1010)MPa.(4)Microstructure and mechanical properties : The features of mechanical properties in these alloys could relate to the order-disorder transition temperatures and spinodal decomposition which occurs at low temperatures.