[Studies on the mechanical properties of dental Ag-Pd-Au-Cu alloys. (Part 1) Effects of age-hardening treatment on the tensile behaviour of alloys (author's transl)].

Tensile behaviour of Ag-Pd-Au-Cu alloys depending on age-hardening was studied by the tensile test with extensometer. The fractured surface of the alloys was observed by the scanning electron microscope. Plastic deformation of alloys was changed from discontinuous yielding to parabolic strain hardening, as the size of precipitate hard particles was grown by aging. There appears to be good correlation between the tensile strength of alloys with aging and the hardness. Strain hardening parameters of the Ludwik, Swift, Voce and Hollomon empirical equations in describing the stress-strain curves were calculated by the least square method. Theoretical tensile strength which was computed from these empirical equations, was good agreement with the tensile test of alloys with aging. But, theoretical uniform elongation tended to elongate. The ratio of tensile strength to proof stress of over-aged alloys was extremely low, as compared with the other alloys. So, over-aging should be avoided to use the alloys in dentistry. If structure of the precipitate particles is controlled by aging temperature and time, the loss of ductility on age-hardening will be considerably eliminated.