抄録
The dental castings contain casting defects such as micro shrinkages, pores, surface roughness, etc. Cyclic stress, that is, fatigue stress due to the mastification is applied to the dental prosthesis in the practical use. Therefore, the effects of the casting defects such as micro shrinkage and pore on the fatigue properties of the cast Ag-Pd-Cu-Au-Zn type alloy were investigated in the comparison with the fatigue properties of the drawn Ag-Pd-Cu-Au-Zn alloy in this study. Moreover, in this study, cast Ag-Pd-Cu-Au-Zn type alloys that were manufactured using a dental casting machine were conducted with two kinds of heat treatments. The fatigue strength of the cast alloy is considerably smaller than that of the drawn alloy. The size of the micro shrinkage affects the fatigue strength of this cast alloy strongly. The fatigue crack of the cast alloy initiates preferentially at the micro shrinkage near the specimen surface. The fatigue strength of solutionized cast alloy is greater than that of as-cast alloy. However, the fatigue strength of the aged cast alloy is nearly the same as that of as-cast alloy. The fatigue strength of this cast alloy can be raised by controlling its microstructure through heat treatments.
