STABILIZATION OF MARTENSITE AND PARENT PHASE ORDERING IN A Cu-Zn-Al ALLOY

The reverse transformation has never occurred in a quenched and aged specimen upon heatingfrom room temperature to 320℃ at which the martensite disappears thoroughly.Both B29R and DO_318R coexist in step-quenched and short-time isothermally treated specimen.As prolonging the isothermal holding,the B29R disappears and DO_318R intensifies.B29R occurs only in specimen quenched and up-quenched immediately to 100—150℃.Rapid quenching from high temperatures will depress the B2→DO_3 ordering but not the A2→B2 one.A plenty enough concentration of vacancy is a necessary condition of occurrence ofB2→DO_3 ordering.The possible mechanism for the stabilization of martensite in aCu-Zn-Al alloy was also discussed.