The Effect of Specific Energy Density on Microstructure and Corrosion Resistance of CoCrMo Alloy Fabricated by Laser Metal Deposition

With the development of modern medical implants, there are significantly increasing demands for personalized prosthesis. Corrosion-resistance and dense cobalt alloy specimens have been successfully fabricated by laser metal deposition. The relationship between specific energy density, microstructure and corrosion resistance of the specimens is investigated. The results show that higher specific energy density promotes the formation of columnar grain and leads to coarse grain size. The evolution and distribution of deposited microstructure from bottom to top are summarized in a metallographic sketch. The corrosion current of deposited specimens increases from 2.071 x 10(-6) A/cm(2) to 6.86 x 10(-5) A/cm(2) and rapidly drops to 9.88 x 10(-7) A/cm(2) with increase of specific energy density from 318.8 J/g to 2752.3 J/g. The columnar and equiaxed structure of deposited specimens have lower corrosion current than mixed structure due to finer grain and less Mo segregation. The deposited have low level metal released because of passive film. The passive film have different formation routes in Hank's solution and acidic saliva. The specific energy density has an important effect on the microstructure of deposited, which improves corrosion resistance and life span in implant.