Date of Award
2024
Document Type
Open Access Master's Thesis
Degree Name
Master of Science in Materials Science and Engineering (MS)
Administrative Home Department
Department of Materials Science and Engineering
Advisor 1
Jaroslaw Drelich
Committee Member 1
Stephen Kampe
Committee Member 2
Jeremy Goldman
Abstract
Zinc (Zn)-based alloys are attractive candidate materials for constructing bioresorbable coronary stents because of their near-ideal corrosion properties and biocompatibility. These alloys are primarily strengthened through alloying and thermomechanical processing by solid solution strengthening, grain refinement, and precipitate strengthening. The microstructural features responsible for these strengthening mechanisms are controlled through the thermal treatment of the alloys. While the static mechanical properties of Zn alloys have been studied, a gap in the literature remains related to their mechanical stability under dynamic loading conditions (fatigue) and creep, especially while subjected to physiological conditions. This work aims to characterize the effects of thermal treatment on the mechanical and corrosion properties of an extruded Zn-Ag-Mn-Cu-Zr-Ti (AMCZT) alloy and the corrosion-fatigue behavior in an extruded Zn-Cu-Mn-Zr (CMZ) alloy. The AMCZT alloy displays unacceptable mechanical properties after extrusion (elongation of 6%), which are improved after thermal treatment at 390°C for 25 minutes (up to 30%) with negligible strength loss. From the AMCZT study, an optimal thermal treatment of 30 minutes at 375°C is designed for Zn alloys with similar compositions. Heat treatment of CMZ serves to dissolve approximately 40% of the precipitate phases in the microstructure of the alloy, which leads to reductions in tensile and yield strength (by 9% and 21%, respectively) but improved fatigue lifetime at all applied stress amplitudes (in-air and in a simulated physiological environment).
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Recommended Citation
Summers, Henry D., "MECHANICAL PROPERTIES AND CYCLING FATIGUE OF ZN-BASED ALLOYS: EFFECTS OF THERMAL TREATMENT", Open Access Master's Thesis, Michigan Technological University, 2024.