SOME ASPECTS OF ANELASTIC AND MICROPLASTIC CREEP OF PURE AL AND 2 AL-ALLOYS

Anelastic creep of pure Al, commercial Al-Cu and a binary Al-Cu alloy has been measured at room temperature by means of a high resolution la ser interferometer. The irreversible component of the deformation was also quantified from measurements of the anelastic creep recovery. The dependence of the deformation-time curves on thermal treatment and co ld work is analyzed. The mechanisms responsible for the room temperatu re anelastic creep are discussed. Materials loaded below their elastic limit can present either a pure anelastic behavior (commercial Al-Cu) or additional viscoelastic creep (pure Al, high purity Al-Cu). For co mmercial Al-Cu, the presence of an irreversible deformation appears to be mainly related to the state of the surface. A viscoelastic after e ffect has been measured for this alloy after a Cu-electroplating treat ment. As a typical result for room temperature creep, the irreversible deformation depends logarithmically on load time.