Effects of cooling rate control during the solidification process on the microstructure and mechanical properties of cast Co-Cr-Mo alloy used for surgical implants

TLDR: In this article, both dendritic structure and equiaxed grain structure are produced in cast Co-Cr-Mo alloy by controlling the cooling rate of castings during the solidification process, to determine whether a significant improvement in the mechanical properties of the alloy can be obtained.

Abstract: Both dendritic structure and equiaxed grain structure are produced in cast Co-Cr-Mo alloy by control of the cooling rate of castings during the solidification process, to determine whether a significant improvement in the mechanical properties of the alloy can be obtained. The different structural characteristics of the two kinds of casting are examined by optical microscopy, scanning electron microscopy and transmission electron microscopy. Tensile and fatigue tests as well as hardness measurement are carried out using individually cast test-pieces. Fracture surface appearance characteristics of tensile and fatigue specimens are also studied. It is concluded that the mechanical properties, including both transient and permanent properties, of the equiaxed grain structure castings obtained by fast cooling are superior to those found in the coarse dendritic structure castings.