title: Magnesium alloys as body implants: fracture mechanism under dynamic and static loadings in a physiological environment.
abstract: It is essential that a metallic implant material possesses adequate resistance to cracking/fracture under the synergistic action of a corrosive physiological environment and mechanical loading (i.e. stress corrosion cracking (SCC)), before the implant can be put to actual use. This paper presents a critique of the fundamental issues with an assessment of SCC of a rapidly corroding material such as magnesium alloys, and describes an investigation into the mechanism of SCC of a magnesium alloy in a physiological environment. The SCC susceptibility of the alloy in a simulated human body fluid was established by slow strain rate tensile (SSRT) testing using smooth specimens under different electrochemical conditions for understanding the mechanism of SCC. However, to assess the life of the implant devices that often possess fine micro-cracks, SCC susceptibility of notched specimens was investigated by circumferential notch tensile (CNT) testing. CNT tests also produced important design data, i.e. threshold stress intensity for SCC (KISCC) and SCC crack growth rate. Fractographic features of SCC were examined using scanning electron microscopy. The SSRT and CNT results, together with fractographic evidence, confirmed the SCC susceptibility of both smooth and notched specimens of a magnesium alloy in the physiological environment.
authors.affiliation: Department of Mechanical & Aerospace Engineering, Monash University, Melbourne, VIC-3800, Australia.
authors.forename: Lokesh
authors.initials: L
authors.lastname: Choudhary
authors.forename: R K Singh
authors.initials: RK
authors.lastname: Raman
mesh_terms: D000497:Alloys / Q000494:pharmacology*; D001826:Body Fluids / Q000187:drug effects; D003343:Corrosion; D006801:Humans; D008274:Magnesium / Q000494:pharmacology*; D008422:Materials Testing; D019736:Prostheses and Implants; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000187:drug effects; D013997:Time Factors; D016474:Weight-Bearing
chemical_list: D000497:Alloys; D008274:Magnesium