1 / 2

(a)

Thermal Stabilization and Mechanical Properties of nc Fe-Ni-Cr Alloys Ronald O. Scattergood, North Carolina State University, DMR 1005677. (a). (b).

dominy
Download Presentation

(a)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Thermal Stabilization and Mechanical Propertiesof nc Fe-Ni-Cr AlloysRonald O. Scattergood, North Carolina State University, DMR 1005677 (a) (b) Small additions of Zr are used to stabilize nanocrystalline (nc) microstructures in ball milled Fe-Ni and Fe-Cr alloys. The efficacy of thermodynamic or kinetic stabilization mechanisms is being evaluated and mechanical properties are being determined. (H. Kotan PhD candidate): TEM video images and X-ray diffraction scans obtained in-situ at temperature are shown in Figures 1a and 1b for Fe91Ni8Zr1. A nc microstructure is maintained up to about 700C. Rapid grain growth occurs with further increase temperature. This results from the bcc -> fcc phase transition. Lower energy fcc grains grow and consume the bcc grains. (M. Saber PhD candidate): A regular solution model has been developed to evaluate thermodynamic stabilization in binary and ternary alloys. Figure 1c shows model results for Zr in Fe, Fe-Cr and Fe-Ni alloys. Cr enhances stabilization whereas Ni reduces it. Figure 1d shows a nc Fe88Cr10Zr2 microstructure retained after annealing at 900C. The Fe98Zr2 counterpart alloy does not maintain this stabilization. (c) (d) Figure 1

  2. Thermal Stabilization and Mechanical Propertiesof nc Fe-Ni-Cr AlloysRonald O. Scattergood, North Carolina State University, DMR 1005677 (a) Education: NSF-REU undergraduate student Chris Ledford is making significant contributions to the research program. He intends to continue as a PhD graduate research student in materials science. Chris developed test procedures and software for conducting shear punch tests on ball milled and hot compacted Fe-Ni-Zr and Fe-Cr-Zr alloys. He conducts mechanical testing and SEM analysis while working with the the graduate research students. Figure 2a shows load displacement test curves (lower right) and typical SEM images of post-test shear failure surfaces. Figure 2b shows a precision loading-frame fixture that Chris is designing and building. It will be used for mechanical testing with mini-tensile test samples. (b) Figure 2

More Related