J. Phys. IV France 05 (1995) C2-199-C2-204
Phase Transitions During Continuous Heating of Martensitic CuAlMn AlloysJ. Dutkiewicz1 and E. Cesari2
1 Institute for Metal Res. Polish Acad. Sci., 30-059 Kraków, ul. Reymonta 25, Poland
2 Physics Department, Univ. of Balearic Islands, Palma de Mallorca, Cra. de Valldemossa km 7.5, Spain
Phase transitions in CuAlMn alloys containing up to 12 at% Mn and 27 at% Al continuously heated up to 550°C were studied using differential scanning calorimetry and transmission electron microscopy. Alloys containing less than 4.8 at% Mn exhibit an exothermal heat effect in the range 280 - 380°C due to γ2 precipitation. The additional endothermal peak above 500°C is caused by DO3 disordering. Alloys of intermediate Mn and Al content show only a reversible martensitic and ordering transformations during repeated cycling in the range - 50 to + 550°C. Alloys of higher Mn (6 - 12 at%) and lower Al content exhibit a diffused exothermal peak in the range 320 - 450°C due to bainitic transformation and a broad endothermal effect above 500°C due to L21/DO3 disordering. Bainitic plates possess 9R structure. They contain more Cu and less Mn and Al when compared to initial alloy compositions. Precipitates of γ2 compositions lie close to its equilibrium phase limits.
© EDP Sciences 1995