Yield stress of nano- and micro-multilayers
- UES Inc., Dayton, OH (United States)
An outline theory is given for the strengthening in polycrystalline and single crystal multilayers. The model is based on the Hall-Petch theory applied to both the soft mode (in plane) and hard mode (cross plane) of deformation. In this theory the parameters to be evaluated are a Taylor factor M, the shear stress {tau}{sub 0} to move a dislocation within a multilayer and {tau}{sup *}, the shear stress needed to push a dislocation over a grain or interphase boundary. All three parameters are material-specific and attention is focused on coherent multilayers of {gamma}TiAl with micron thick layers and Cu-Ni with nanometer thick layers. M and some components of {tau}{sup *} are estimated classically. The remaining components of {tau}{sup *} and some components of {tau}{sub 0} are estimated from embedded atom simulations. The model captures the main experimental facts, that {gamma}TiAl is plastically very anisotropic with a rising yield stress as the lamellar thickness is refined and that Cu-Ni displays a peak in the yield stress at a layer thickness of approximately 10 nm.
- Sponsoring Organization:
- Department of the Air Force, Washington, DC (United States)
- OSTI ID:
- 490767
- Report Number(s):
- CONF-960401-; ISBN 1-55899-337-1; TRN: IM9729%%18
- Resource Relation:
- Conference: Spring meeting of the Materials Research Society (MRS), San Francisco, CA (United States), 8-12 Apr 1996; Other Information: PBD: 1996; Related Information: Is Part Of Layered materials for structural applications; Lewandowski, J.J. [ed.] [Case Western Reserve Univ., Cleveland, OH (United States)]; Ward, C.H. [ed.] [Air Force Office of Scientific Research, Bolling AFB, DC (United States)]; Jackson, M.R. [ed.] [General Electric Corporate R and D, Schenectady, NY (United States)]; Hunt, W.H. Jr. [ed.] [Alcoa Technical Center, Alcoa Center, PA (United States)]; PB: 325 p.; Materials Research Society symposium proceedings, Volume 434
- Country of Publication:
- United States
- Language:
- English
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