Mehanička svojstva i mikrostrukturna karakterizacija Au-Pt dentalne slitine

Development of a dental alloy with high Au content is based on the ternary system of Au-Pt-Zn with a nominal composition of 86,9Au-9,9Pt-1,5Zn, and about 1,5 wt.% micro-alloying elements (In, Ir, Rh). The results analyses of different heat-treated states showed that the optimal mechanical properties and hardness of an Au-Pt-Zn alloy can be reached with combinations of heat treatment for 20 minutes at 723 K and then slowly cooling, if the alloy was annealed at 1223 K for 30 minutes and the water quenched. Research results confirmed that the microstructure of the Au-Pt-Zn alloy consists of two phases: α1-phase rich in Au (main phase) and α2-phase rich in Pt (minor phase). During XRD analysis and use of the Rietveld method, it was found that the α1-phase content is about 98,5 wt.% while the content of α2-phase is 1,5 wt.%. STA analyses show that the Au-Pt-Zn alloy has a solidus temperature of about 1292 K and a liquidus temperature of about 1412 K. Razvoj dentalne slitine s visokim sadržajem zlata zasnovan je na ternarnom sustavu Au-Pt-Zn s nominalnim sastavom 86,9Au-9,9Pt-1,5Zn i oko 1,5 mas. % mikrolegirajučih elemenata (In, Ir, Rh). Rezultati analize su pokazali da se u slučaju slitine odžarene kod 1223 K u trajanju od 30 minuta i zakaljena u vodi optimalna mehanička svojstva i tvrdoća Au-Pt-Zn slitine mogu postići kombinacijom toplinske obrade na 720 oC u trajanju 20 minuta s naknadnim sporim hlađenjem. Rezultati istraživanja su potvrdili da se mikrostruktura Au-Pt-Zn slitine sastoji od dvije faze: α1-faze bogate sa zlatom (primarna faza) i α2 - faze bogate s platinom (sekundarna faza). Tijekom XRD analize i primjenom Rietveldove metode utvrđeno je da je sadržaj α1-faze oko 98,5 mas. %, dok je sadržaj α2-faze iznosio oko 1,5 mas. %. STA analiza je pokazala da je Au-Pt-Zn slitina imala solidus temperaturu oko 1292 K, a likvidus temperaturu oko 1412 K.