Hardness of Cu ? Mn ? Al alloys as a function of the annealing temperature in the bphase

PRADO, M. O.; TOLLEY, ALFREDO

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 1999 vol. A273 p. 590 - 594

0921-5093

Samples of Cu ? 10.0at.%Mn ? 18.8at.%Al and Cu ? 11.0at.%Mn ? 18.1at.%Al alloys were prepared in the metastable austenitic phase, by quenching from 1123 K into water at room temperature. The as quenched samples were found to be L21ordered. Aging of these alloys at different temperatures induced an evolution of the microhardness. These icrohardness changes are interpreted using the information from X-ray diffraction (XRD), martensitic transformation temperature measurements, transmission electron microscopy (TEM) and microanalysis using scanning electron microscopy (SEM). Changes in microhardness at low temperatures are correlated with the martensitic transformation temperature Msprovided that Ms is close to room temperature. Microhardness changes at higher temperatures are caused by the decomposition of the bphase. The kinetics ofbphase decomposition was followed measuring its 200 XRD peak intensity. The experiments suggest that the last vestiges of bphase are L21 long range ordered and that anafcc phase is formed during the first stages of decomposition. © 1999 Elsevier Science S.A. All rightsreserved.