Creep Versus Microstructure of γ2-Containing Amalgams

Abstract

An analysis of the relationship between creep and microstructural characteristics of several gamma2-containing amalgams showed the grain size of the Ag-Hg phase (gamma1) to be a predominant factor influencing creep. When gamma1 grain size is increased, creep is reduced.

On Creep Mechanisms in Amalgams

“…Pre-polished vertical surfaces of nearly cylindrical creep specimens contain substantial offsets indicating pronounced grain-boundary sliding in the Ty phase. 4. The creep rate increases with decreasing grain size in the Tyi phase.…”

Effect of Time at 37°C on the Creep and Metallurgical Characteristics of Amalgam

“…However, there are other metallurgical factors that could be implicated in a decrease in creep with aging at 370C. Creep is influenced by the amount of Sn in the -Yi phase (Mahler and Adey, 1979) and also by the grain size of y, (Mahler et al, 1977), yet neither of these factors has been measured after storage at 370C for extended time periods. Jensen and Jorgensen (1978) measured lattice parameter changes in the y, phase of four low-copper amalgams after storage for six months at 370C.…”

Factors Influencing the Creep of Dental Amalgam

“…The grain size of y1 has been shown to influence creep in y 2-containing amalgams (Mahler et al, 1977) and was significant in this group of alloys as well. Hg content reflects the amount of y1 because most of the Hg in the set amalgam is in this phase.…”

“…Because this paper will frequently refer to the various metallic phases of dental amalgam, these phases and their descriptions appear in Table 1. By measuring the creep ofthe y, y 1, and Y2 phases separately, Espevik (1977) concluded that the creep of amalgam is primarily due to creep of the y I matrix phase. Factors that have been shown to influence creep include final Hg content of the set amalgam (Mahler and Van Eysden, 1969), Sn in the y I phase (Mahler and Adey, 1979), Zn in the y1 phase (Johnson and Paffenbarger, 1980), grain size ofy 1 (Mahleret al, 1977), amount ofthe Y2 phase (Mahler et al, 1977;Osborne and Gale, 1990), and the amount ofthe y phase (Mahler et al, 1977). In addition, the presence of small pe crystals in the y1 matrix has been suggested as having an influence on creep (Okabe et al, 1978).…”