Can shape memory alloys recover from plastic deformation?

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Discussion Overview

The discussion revolves around the behavior of shape memory alloys (SMAs) in relation to plastic deformation, specifically whether these materials can recover from such deformation and the underlying mechanisms involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant inquires about the dislocation of atoms or crystals during the plastic deformation of metals.
  • Another participant confirms that dislocation occurs in plastic deformation, referencing external sources for further information.
  • A subsequent participant introduces the concept of shape memory alloys, explaining that they utilize phase transformation to return to a previous shape after being subjected to plastic deformation.
  • The example of NiTi (Nitinol) is provided as a typical shape memory alloy that can recover from significant plastic strain, suggesting a unique mechanism compared to conventional metals.

Areas of Agreement / Disagreement

The discussion includes multiple viewpoints regarding the behavior of materials under plastic deformation, with no clear consensus on the implications for shape memory alloys and their recovery capabilities.

Contextual Notes

Participants have not fully explored the assumptions regarding the mechanisms of plastic deformation in relation to shape memory alloys, and there may be limitations in the definitions used for dislocation and recovery processes.

e150031
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Hi,

I want to learn that do atoms or crystals dislocate in the plastic deformation of metals.
 
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e150031 said:
Hi,

I want to learn that do atoms or crystals dislocate in the plastic deformation of metals.

Yes (if I have interpreted your question correctly).

http://en.wikipedia.org/wiki/Dislocation

CS
 
granpa said:
what about memory metal?

In a shape memory alloy phase transformation is utilized to return to a shape which existed before they were subjected to plastic deformation (via a thermally activated process). Typical example being NiTi (or Nitinol commerically), which is one of the alloys which can recover from enough plastic strain to be viable in various applications. So not really changing the underlying mechanisms for plastic deformation, but adding a twist to it.

http://web.archive.org/web/20030605085042/http://www.sma-inc.com/SMAPaper.html
 

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