Flow and Fracture of Dental Alloys Determined by a Microbend Tester

¹ University of Michigan School of Dentistry, Ann Arbor, Michigan

The black areas of the sound castings, which were identified by Badger and Sweeney as eutectoid areas, comprised the most brittle phase in cobalt-base alloys.

The matrix of cobalt-base alloys was found to be quite ductile and to withstand a considerable amount of bending. The presence of microporosities in the cast pieces was the first cause of fractures when the specimens were bent. When the sound cobalt-base castings did not possess dark eutectoid areas, the fracture initiated at the grain boundary.

Gold alloys tested did not fracture in the same manner as cobalt-base specimens. They crushed and deformed until they broke.

Further investigation in microbend tests may yield some useful results for dentistry.