ISOTHERMAL DECOMPOSITION OF THE b' PHASE IN Cu-Zn-Al SHAPE-MEMORY ALLOYS

The decomposition of the b' phase in shape-memory alloys was studied. The B2®DO3 order transition was not completely suppressed by quenching in icy water. The aging process at temperatures below 400°C involved the formation of bainite or a phase. In specimens aged at higher temperatures the a phase was observed. The activation energies of a precipitation in the Cu-25.7Zn-3.1Al alloy and Cu-17.9Zn-5.4Al alloy were determined to be 109.85 kJ mol -1 and 132.12 kJ mol -1 , respectively. The formation of g precipitates was not observed. Key words: shape-memory alloys, decomposition, precipitation Raziskana je bila razgradnja b'-faze v zlitinah s spominom 4Al. Premena urejenosti B2®DO3 ni bila popolnoma prepre~ena s kaljenjem v ledeni vodi. Pri staranju pri ni`ji temperaturi od 400°C je nastal bainit ali a-faza. V vzorcih,`arjenih pri vi{jih temperaturah, smo na{li a-fazo. Aktivacijske energije za a-izlo~anje v Cu-25,7Zn-3,1Al in Cu-17,9Zn-5,4Al so bile 109,85 kJ/mol oz. 132,12 kJ/mol. Nastanka g-izlo~kov nismo opazili