SUBJECT: | Ph.D. Proposal Presentation | |
BY: | Robert Caraway | |
TIME: | Thursday, January 18, 2024, 2:00 p.m. | |
PLACE: | MARC Building, 114 | |
TITLE: | Enabling Tensile Strength in Additively Manufactured Nickel-Titanium Shape Memory Alloys | |
COMMITTEE: | Dr. Aaron Stebner, Chair (ME) Dr. Richard Neu (ME) Dr. Ting Zhu (ME) Dr. Kyle Saleeby (ME) Dr. Preet Singh (MSE) |
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SUMMARY
To date, ultimate tensile strength (UTS) within additively manufactured (AM) nickel-titanium (NiTi or Nitinol) has not been demonstrated at levels satisfactory for use in many commercial applications, especially medical and aerospace. AM NiTi parts have not yet reached UTS of 1000 MPa, but these industries desire 1200 MPa or higher. Building on the work demonstrating the mechanism by which this degradation of mechanical properties occurs will allow for progress towards more usable AM parts. Evidence suggests that one cause of this insufficient UTS could be oxygen based, ceramic inclusions, specifically Ti4Ni2O and/or TiO2. Other possible mechanisms are residual stress, surface defects, Ni3Ti intermetallics, over-coarsened Ni4Ti3 precipitates, solute segregation, porosity, unmolten powder, ceramic inclusions (carbides, oxides, etc), and control of these will allow testing the hypothesis that the major cause is oxide phases. |