Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10620268 | Acta Materialia | 2013 | 14 Pages |
Abstract
A bulk nanostructured alloy with the nominal composition Cu-30Zn-0.8Al wt.% (commercial designation brass 260) was fabricated by cryomilling of brass powders and subsequent spark plasma sintering (SPS) of the cryomilled powders, yielding a compressive yield strength of 950Â MPa, which is significantly higher than the yield strength of commercial brass 260 alloys (â¼200-400Â MPa). Transmission electron microscopy investigations revealed that cryomilling results in an average grain diameter of 26Â nm and a high density of deformation twins. Nearly fully dense bulk samples were obtained after SPS of cryomilled powders, with average grain diameter 110Â nm. After SPS, 10Â vol.% of twins is retained with average twin thickness 30Â nm. Three-dimensional atom-probe tomography studies demonstrate that the distribution of Al is highly inhomogeneous in the sintered bulk samples, and Al-containing precipitates including Al(Cu,Zn)-O-N, Al-O-N and Al-N are distributed in the matrix. The precipitates have an average diameter of 1.7Â nm and a volume fraction of 0.39%. Quantitative calculations were performed for different strengthening contributions in the sintered bulk samples, including grain boundary, twin boundary, precipitate, dislocation and solid-solution strengthening. Results from the analyses demonstrate that precipitate and grain boundary strengthening are the dominant strengthening mechanisms, and the calculated overall yield strength is in reasonable agreement with the experimentally determined compressive yield strength.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Haiming Wen, Troy D. Topping, Dieter Isheim, David N. Seidman, Enrique J. Lavernia,