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Bio-corrosion studies of biodegradable alloys in the Mg-Y-Sr and Mg-Zn-Sr system

Hwang, Li-Fu (2019) Bio-corrosion studies of biodegradable alloys in the Mg-Y-Sr and Mg-Zn-Sr system. Master's Thesis, University of Pittsburgh. (Unpublished)

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Pure magnesium possesses similar mechanical properties compared to natural human bone, which helps to avoid the negative effects of stress shielding induced typically by other high modulus bio-inert metallic implants. Magnesium is also considered a biodegradable metal, its degradation in-vivo aids in bone regeneration and reduces the need for implant removal surgeries. However, controlling the corrosion rate and reduction of the biotoxicity are the important goals for optimizing Mg alloys for implant application. In this study, Mg-Zn-Sr and Mg-Y-Sr alloys were researched as biodegradable biomedical materials. Zn and Sr are useful alloying elements for refining the grains in Mg alloys. Y serves as an effective solid solution hardener, arising from the large difference in atomic radii between Mg and Y atoms. The two alloys were received our collaborator in India following synthesis using melting followed by squeeze casting. The results of x-ray diffraction patterns and scanning electron microscopy were used to understand the microstructural/composition-functional relationship of the Mg-Zn-Sr and Mg-Y-Sr alloy system. A higher amount of strontium leads to the formation of a secondary Mg17Sr2 phase along the grain boundaries. The corrosion properties of these alloys were analyzed in-vitro by immersion and electrochemical tests. The electrochemical corrosion results demonstrated that incorporation of 1 wt% Sr lead to a decrease in corrosion current (Icorr) and corrosion rates as compared to pure Mg. Further addition of Sr to the Mg-Zn-Sr and Mg-Y-Sr alloys lead to an increase in corrosion rate due to the presence of higher amounts of secondary phase precipitates. The biomechanical properties and in-vitro cell-toxicities of these alloys should be evaluated in future for their possible applications as a bone fixation device and bone graft.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairKumta,
Committee MemberLee, Jung-Kunjul37@pitt.eduJUL370000-0002-7778-7679
Committee MemberNettleship,
Date: 27 June 2019
Date Type: Publication
Defense Date: 1 April 2019
Approval Date: 27 June 2019
Submission Date: 30 March 2019
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 68
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering and Materials Science
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Microstructure, Corrosion test,Biomaterials
Date Deposited: 27 Jun 2019 15:59
Last Modified: 27 Jun 2019 15:59


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