A comparative study of the corrosion resistance of incoloy MA 956 and PM 2000 superalloys

Maysa Terada,Isolda Costa,Rogério Albuquerque Marques,Marina Magnani,Angelo Fernando Padilha

doi:10.1590/s1516-14392010000400002

Abstract

Austenitic stainless steels, titanium and cobalt alloys are widely used as biomaterials. However, new medical devices require innovative materials with specific properties, depending on their application. The magnetic properties are among the properties of interest for some biomedical applications. However, due to the interaction of magnetic materials with Magnetic Resonance Image equipments they might used only as not fixed implants or for medical devices. The ferromagnetic superalloys, Incoloy MA 956 and PM 2000, produced by mechanical alloying, have similar chemical composition, high corrosion resistance and are used in high temperature applications. In this study, the corrosion resistance of these two ferritic superalloys was compared in a phosphate buffer solution. The electrochemical results showed that both superalloys are passive in this solution and the PM 2000 present a more protective passive film on it associated to higher impedances than the MA 956.

Highlights

Metallic materials are widely used in dental implants, orthodontic appliances as bands, arch wires, ligature wires, hooks, tubes, brackets and springs, and orthopedic devices as implants and prosthesis for fractured bones healing[1]
According to results reported in literature[16], the model proposed in Figure 2a represents the Incoloy MA 956 immersed in Hankssolution and characterizes a passive system[16,17]
It has been stated that the presence of only one time constant in the Electrochemical impedance spectroscopy (EIS) results of the Incoloy MA 956 is due to the presence of an alumina layer on the alloy surface[9]

Summary

Introduction

Metallic materials are widely used in dental implants, orthodontic appliances as bands, arch wires, ligature wires, hooks, tubes, brackets and springs, and orthopedic devices as implants and prosthesis for fractured bones healing[1]. The use of ferromagnetic alloys in orthopedic area is undesirable due to the size of the implant[2,3], that can move or heat during MRI tests[4]. It was proven that small devices, as dental implants and dental prosthesis attachments, are not affected by MRI tests[5,6] Both superalloys investigated in this study, Incoloy MA 956 and PM 2000, are ferromagnetic. These alloys were produced by mechanical alloying followed by hot extrusion. They have similar chemical compositions, but the literature shows differences in their kinetic oxidation and the oxide particle morphology, comparing samples heat treated at 1,100 °C for 100 hours. The PM 2000 has been investigated for biomaterials applications, and its mechanical[12] and magnetic properties have been investigated[13] as well its biocompatibility[14,15]

Experimental

Results and Discussion

Conclusions