@article {1396,
	title = {Creep resistance of bulk copper{\textendash}niobium composites: An inverse effect of multilayer length scale},
	journal = {Acta Materialia},
	volume = {176},
	year = {2019},
	pages = {189{\textendash}198},
	abstract = {<p>
	Metallic multilayer systems show promising performance in extreme environments, with high stability of bi-metal interfaces down to nanometer length scales. The creep behavior of bulk, accumulative roll bonded (ARB) Copper\&ndash;Niobium (Cu\&ndash;Nb) composites has been studied at 400 \&deg;C as a function of layer thickness, ranging from 2 \&mu;m to 65 nm. Similar to single phase metallic systems, three regimes are observed during creep: transient, steady-state and tertiary. The mechanism controlling minimum creep rate for all conditions tested has a strong dependence on stress, consistent with dislocation-dominated creep. Unlike the conventional effect of grain size on creep resistance, this study reveals that decreasing length scale increases creep resistance.
</p>
},
	keywords = {Creep, Cu-Nb, Length scale, Multilayer},
	issn = {13596454},
	doi = {10.1016/j.actamat.2019.06.029},
	url = {https://doi.org/10.1016/j.actamat.2019.06.029},
	author = {Avallone, Jaclyn T. and Nizolek, Thomas J. and Bales, Benjamin B. and Pollock, Tresa M.}
}
@article {1381,
	title = {A model for high temperature deformation of nanolaminate Cu-Nb composites},
	journal = {Materials Science and Engineering A},
	volume = {761},
	year = {2019},
	pages = {138016},
	abstract = {<p>
	Nanolaminate composites with layer thicknesses down to 65 nm display conventional 3 stage creep behavior with creep resistance increasing as layer thickness decreases. A model for the time dependent high temperature deformation response of Cu-Nb composites is developed, and compared to creep tests performed on multilayers fabricated via accumulative roll bonding (ARB). The model assumes a continuous laminate structure of 50\% Cu and 50\% Nb in which deformation is controlled by stage II creep for the copper (\&epsilon;˙cr=A\&sigma;n) and plasticity in Nb. Regimes in which composite steady-state creep at constant stress can be achieved are identified. The modeling illustrates that strain-hardening in the niobium plays a critical role in the transient response of the multilayer, which can dominate the creep lifetime. The combination of experiments and models strongly suggest that dislocation climb mechanisms in the copper control the time-response at 400 oC for all layer thicknesses tested.
</p>
},
	keywords = {Creep model, Cu-Nb, Multilayer composite, Strain hardening},
	issn = {09215093},
	doi = {10.1016/j.msea.2019.06.026},
	url = {https://doi.org/10.1016/j.msea.2019.06.026},
	author = {Avallone, Jaclyn T. and Nizolek, Thomas J. and Pollock, Tresa M. and Begley, Matthew R.}
}
