Growth twins are scarcely observed in metals with high stacking fault energy, such as pure Al. In this study, however, we report the observation of growth twins in sputtered polycrystalline Al films on amorphous substrates and a majority of these growth twins are inclined to the growth direction (inclined twins). Although the fraction of twinned grains is low in general, it increases monotonically with increasing film thickness, reaches a maximum at the film thickness of 80 nm, and decreases gradually thereafter in the thicker films. The nucleation mechanism for the inclined twins is compared with that of the parallel growth twins in Al. Different twin formation mechanisms are discussed. This study provides an alternative perspective to evaluate the formation of growth twins in metals with high stacking fault energy.
Bibliographical noteFunding Information:
X.Z. and S.X. acknowledge financial support by DoE-OBES under Grant No. DE-SC0010482 . Y.C. is partially supported by NSF-CMMI under Grant No. 1129065 . H.W. acknowledges the support from the Office of Naval Research (under Dr. Lawrence Kabacoff and Dr. Antti Makinen N000141310555 ). Z.F. is supported by NSF-CMMI under Grant No. 1161978 . Acknowledgment is also made to the donors of the American Chemical Society Petroleum Research Fund ( 53741ND10 ) for partial support of J.L. for part of sputtering depositions during this research. Access to the DOE-Center for Integrated Nanotechnologies (CINT) at Los Alamos and Sandia National Laboratories and the microscopes at the Microscopy and Imaging Center at Texas A&M University are also acknowledged.
- Defect nucleation kinetics
- Growth twin
- Nanotwinned Al