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NiCrMo alloys are popular as non-precious dental casting alloys and appreciated specially in developing nations. A number of elements may be alloyed to achieve enhanced characteristics suitable for dental restorations. In this study NiCrMo dental casting alloy was alloyed with cerium to improve mechanical, metallurgical and biomedical characteristics. Three alloys were produced by vacuum induction melting technique. These cast alloys were tested for melting range, phase analysis, microstructure, mechanical and wear characteristics, corrosion behavior, coefficient of thermal expansion and biocompatibility properties. Test results revealed that 0.4% cerium addition in NiCrMoB alloy substantially improved the mechanical, metallurgical and corrosion characteristics of the cast alloy without compromising the biocompatibility and melting characteristics of the alloy. Mechanical testing and tribological results pointed out that the NiCrMoB alloy with 0.4% addition of cerium possessed tensile strength up to 515 MPa with impact strength around 7 J, while average coefficient of friction was calculated to be 0.1715; that was least of the investigated alloys. Corrosion rate for the alloy was found to be 25.92 × 10−3 mils per year that was also the least among the investigated alloy samples.

Objective To evaluate the influence of different heat treatments on the corrosion behavior of a new Pd⁃ Ag⁃In⁃Ga alloy. Methods The corrosion of a new Pd⁃Ag⁃In⁃Ga alloy was tested according to ISO 10271：2001/cor.1: 2005(E). Taken as comparison, a commercial high⁃palladium alloy (Spartan® Plus) was also employed in the study. For electrochemical corrosion test, the open ⁃circuit potential (Eocp) and potentiodynamic polarization curve were recorded and then the electrochemical parameters, namely corrosion potential (Ecorr) and corrosion current density (Icorr) calcu⁃ lated. The surfaces of the specimens that before and after corrosion test were observed by scanning electron microscopy (SEM). Results Both of the high ⁃ palladium alloys had lower corrosion tendency and higher corrosion resistance by heat treatment in the ISO 10271 electrochemical corrosion test. For both alloys, heat treatment at 500 ℃ was found to be effective in improving the corrosion resistance as the best datas of electrochemical parameters (Eocp, Ecorr, Icorr) were detected among the four temperature groups. However, no evidence showed that there was significant difference in corrosion resistance between the two alloys. Comparison of surface morphology of the specimens before and after electro⁃ chemical experiments by SEM demonstrated that all groups of the two alloys were visible of pitting corrosion and crevice corrosion phenomenon that gradually became less with increasing heat treatment temperature. Horizontal comparing among the groups of the two alloys, no apparent differences in the distribution of pitting and crevice corrosion was found. Conclusion The variation in compositions of high⁃palladium alloys did not cause significant difference in corro⁃ sion behavior due to the identical palladium matrix. The similarity in corrosion behavior among the two high⁃palladium alloys might be attributed to the predominant palladium content.