Location: Zoom
Add to Calendar 2020-09-24T15:00:00 2020-09-24T15:00:00 America/New_York North American Materials Colloquium Series (NAMCS) Title: Imaging of Chemical Short-range Order and Its Impact on Deformation in Structural Alloys Speaker: Ruopeng Zhang, Ph.D. Candidate, University of California, Berkeley, Email address: warpoin@berkeley.edu Zoom

Title: Imaging of Chemical Short-range Order and Its Impact on Deformation in Structural Alloys

Speaker: Ruopeng Zhang, Ph.D. Candidate, University of California, Berkeley, Email address: warpoin@berkeley.edu

Abstract: Chemical short-range order (SRO) of atoms within a nominally single-phase solid solution is known to significantly impact the plastic deformation of alloys. While associated phenomena, such as planar dislocation slip morphology and ranging stacking fault energies, have been indirectly related to deformation behaviors, direct observation of the SRO microstructure at the nanoscale remains unexplored. Here we report the direct observations of SRO and associated deformation features in a Ti-Al alloy and a medium entropy alloy using energy-filtered dark field imaging. The observation revealed the domain clusters structure of the SRO and verified that the degree of SRO could be tailored by the thermomechanical history of the alloys. The impact of SRO on the deformation behaviors of the alloys, including dislocation motions and deformation twinning, are investigated at different scales. The atomistic interaction between SRO and deformation is probed via a full strain tensor mapping method based on four-dimensional scanning transmission electron microscopy, revealing the evolution of local bonding environment that is responsible for the slip planarity. The tool set developed in the current study grants the ability of conduct quantitative analysis of SRO and shines light upon a new avenue to engineer desirable performance of structural alloys.

Instructions Attending Synchronous (Live) Webinars

  1. Go to the URL a few minutes before 3:00 pm ET on Thursdays (beginning September 10) or 4:00 pm ET on Fridays (beginning September 11)
  2. The content of the seminar is the same on Thursdays and Fridays, but the Q&A, attendees, and moderators will differ.
  3. Participants will be added to the webinar as an “attendee”. Participants will not be on camera, and their microphone will be muted.
  4. The format for the webinar is as follows:
  • The webinar will begin with a live introduction of the speaker.
  • Each speaker has prerecorded their talk ahead of time to limit technical difficulties. The speaker will be available to answer questions typed in the Q&A while the presentation is playing. In addition, the speaker will be available to answer questions after the presentation is finished playing.
  • After the seminar is played, the moderator will read brief Q&A questions to the speaker, but attendees with more involved questions can request access to their microphone to ask a question by either raising their hand or by indicating this preference at the end of a typed question in the Q&A.