A New Dental Superalloy System: II. Mechanical Properties

Cobalt-base alloys strengthened by inter-metallic compounds of tantalum were pre-pared and tested. Some of the alloys were stronger and more ductile than conventional base-metal alloys. Theoretical considerations that lead to the design of strong and ductile cobalt (Co)-base alloys were discussed in part I of this series of articles.' It was hypothesized that the composition 40 Co-30 nickel (Ni)-30 chromium (Cr) is an acceptable compromise for the require-ments of an alloy base. It also was found that tantalum (Ta) may have the qualities that are acceptable for an additional ele-ment; it reacts with Co to form intermetal-lic compounds that should produce a strong and ductile alloy. The purpose of this investigation was to test the validity of this hypotheses. Alloys that were designed according to the ideas presented in part I were prepared and the mechanical properties of these alloys were tested. Materials and Methods The compositions of the alloys that were prepared in this study are found in the table. The metals used in these compositions were high purity metals with more than 99.9 % pure elements. Co and Ni were sup-plied in the form of small shots. Cr was supplied in sheet form and was crushed to smaller pieces (2 X 2 mm). Ta was pro-vided by thin wires that were cut to shorter pieces (2 mm). The ternary alloy elements, Based on a dissertation submitted in partial fulfill-ment of the PhD degree in dental materials and engi-neering materials at the University of Michigan, 1971. Part II was presented at the 50th general meeting o