Nanolayered metal-ceramic composite systems provide the possibility to produce new materials with exceptional strength, toughness, and radiation resistance not exhibited by their individual constituents. The unusual behaviors are frequently attributed to the high density of internal interfaces. Most layered structures studied to date contain sharp interfaces and the synthesis of more diffuse interfacial structures, where the interface is graded out of the interface plane, has not been deeply explored. Here we show how neutron reflectometry was used to study the structure of magnetron sputter deposited titanium and titanium nitride (Ti/TiN) layers as a function of deposition parameters: temperature, rate of N2 flow or pressure, electrical bias applied to the sample, and orientation of the ion source relative to the sample. These different deposition and post-processing strategies resulted in profound changes in the structure of the interfacial region between the two components in Ti/TiNx bilayers. The results show that temperature and low step-wise N2 flow rates, but not electrical bias, can form graded interfaces in a controlled manner.
Bibliographical noteFunding Information:
The authors gratefully acknowledge support from the U.S. Department of Energy , Office of Science, Office of Basic Energy Sciences. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under Contract DE-AC52-06NA25396. This work also benefited from the use of the Lujan Neutron Scattering Center at LANSCE.
- Composite materials
- Engineered interfaces
- Neutron reflectivity
- Titanium nitride