Scand.J. Dent. Rei. 1977: 83: 4 9 2 - 4 9 5 IKi'\' '^^'(>^c^s: denial affislgaf/i]
Creep of dental amalgam and its phases S. ESPEVIK NIO.M-Scandinavian Institute of Dentai Materials, Oslo, Norway
AB.STRACT - The intention of the study was to evaluate creep as a function of temperature and stress, atid to determine creep rate of compounds with a cotnposition equivalent to the y, y,, and YI phases in dental atnalgam. The results were consistent with a creep model in which the deformation takes place in the y, phase, and is dominated by glide pileups of dislocations in grain boundaries. (Acceptedfir publication !i May 1977)
The creep of dental amalgam as a funct:ion of stress and temperature has previously been studied by DiCKSON, OGLESBY & DAVENPORT (1968). They found that the steady state creep rate was thennally activated with an activation energ)' of 35 kcal/mole, and has a stress, ff, dependence where the stress exponent, n, in a" was 3.45. They concluded that climb of dislocation was a possible creep mechanism. The effective stress (applied stress minus an internal stress component) was considered when VRIJHOEF & DRIESSENS (1974) evaluated creep as a function of stress and temperature of dental amalgam. They concluded that creep of dental amalgam was determined by the low melting phases. It was the purpose of this investigation to evaluate creep as a function of temperature and stress and to determine
the creep rates of compounds with a composition equivalent to the y, y,, and y^ phases in dental amalgam.
IVIaterial and mettiods Details pertaining to the alloys used in the study are listed in Tabie 1. The amalgam samples were prepared according to the American Dental Association Specification No. 1 {Guide to denial materials and devices 1974), and stored 7 d at 37°C prior to testing. Two samples for each test condition were used. The creep tests were condticted at constant load, and the data were presented as secondary steady state creep rate determined at strain
Creep of dental amalgam and its phases S. ESPEVIK NIO.M-Scandinavian Institute of Dentai Materials, Oslo, Norway
AB.STRACT - The intention of the study was to evaluate creep as a function of temperature and stress, atid to determine creep rate of compounds with a cotnposition equivalent to the y, y,, and YI phases in dental atnalgam. The results were consistent with a creep model in which the deformation takes place in the y, phase, and is dominated by glide pileups of dislocations in grain boundaries. (Acceptedfir publication !i May 1977)
The creep of dental amalgam as a funct:ion of stress and temperature has previously been studied by DiCKSON, OGLESBY & DAVENPORT (1968). They found that the steady state creep rate was thennally activated with an activation energ)' of 35 kcal/mole, and has a stress, ff, dependence where the stress exponent, n, in a" was 3.45. They concluded that climb of dislocation was a possible creep mechanism. The effective stress (applied stress minus an internal stress component) was considered when VRIJHOEF & DRIESSENS (1974) evaluated creep as a function of stress and temperature of dental amalgam. They concluded that creep of dental amalgam was determined by the low melting phases. It was the purpose of this investigation to evaluate creep as a function of temperature and stress and to determine
the creep rates of compounds with a composition equivalent to the y, y,, and y^ phases in dental amalgam.
IVIaterial and mettiods Details pertaining to the alloys used in the study are listed in Tabie 1. The amalgam samples were prepared according to the American Dental Association Specification No. 1 {Guide to denial materials and devices 1974), and stored 7 d at 37°C prior to testing. Two samples for each test condition were used. The creep tests were condticted at constant load, and the data were presented as secondary steady state creep rate determined at strain
