INTRODUCTION
Implants are fabricated from a wide variety of materials, including metals, polymers, ceramics and their
composites. Among these materials, metals are an important group [1]. Cobalt chrome alloys are used widely for medical
prosthesis such as hip and knee replacements, dental devices and support structures for heart valves because they have a
great biocompatibility and spontaneous chromites formation of a passive layer which provides the material high corrosion
resistance [2]. They are used where high stiffness, or highly polished, and extremely wear resistant material is required.
Wear resistance, mechanical properties, biocompatibility and corrosion resistance may be influenced by the microstructure
which depends on the thermal treatment applied to the material [3].
Yttrium was first discovered by Johan Gadolin. The physical appearance is a bright silvery surface like other
metals and it s also prepared as a dark gray to black powder with a bit of shine. Like any other rare earth metals yttrium has
many uses and the most common use iYttrium phosphors have long been used in color televisions sets and in computer monitors [4, 5].
No research has focused on Yttrium into CoCrMo matrix to improve the physical and chemical properties without
affecting the alloy. This research highlights to improve the mechanical and electrochemical properties of CoCrMo alloy by
addition different percentages of yttrium (C1 =0.5%Y, C2= 1%Y, C3= 1.5%Y & A= master alloy).s in phosphors. A phosphor is a material that shines when struck by electrons.