XRD spectrum of as-deposited film. Note the amorphous scattered signal indicative of room temperature sputtered NiTi. Heat treated spectrum shifted for clarity.
SEM image of an array of irradiated regions. Irradiated regions are with uniform energy density. Each square region represents one energy density.
Schematic representations of the (a) PM, (b) NCM, and (c) CM regimes.
Reflectivity spectrum for an amorphous and a number of heat treated films. This change in reflectivity, due to oxidation, particularly at , is consistent with observed enhanced laser-film energy coupling (Ref. 29).
XPS spectrum of heat treated film confirming presence of .
XRD spectra for the as-deposited amorphous spectrum and the room temperature, laser treated specimen (completely melted) confirming crystallization as well as heterogeneous nucleation. Additionally, it is seen that a metastable phase results due to the exceedingly high quench rate.
XRD spectra depicting the thermally induced phase transformation. Note that emergence of the austenitic phase upon heating and subsequent disappearance upon cooling. The persistence of the  austenitic peak suggests a phase mixture of austenite and martensite upon cooling back down to room temperature.
XRD spectra for room temperature and substrate temperature. Room temperature processing results in metastable phase formation, while an elevated substrate temperature processing results in the formation of austenite. Note that both films were laser treated above their respective complete melt thresholds and result in highly textured films implying heterogeneous nucleation.
Schematic load curve for typical nanoindentation experiment. Note that the total energy input to the system is equal to the sum of the dissipated and recovered energy.
Load curve comparisons between specimens processed at room temperature , , and . Note that all specimens presented here were laser treated with energy densities above their respective CMTs.
Energy recovery ratio as a function of maximum indenter load for films laser processed at room temperature , , and . It is seen here that the film processed at recovers significantly more energy upon unloading due to its superelastic response. Note that all specimens presented here were laser treated with energy densities above their respective CMTs.
Load responses of laser treated and untreated films for elevated substrate temperatures of and . Note the increased slope as well as increased depth recovery for the laser treated,  textured film treated at . The load response of a precrystallized (no laser treatment) film at is also included for reference.
Effective film modulus for films laser processed at room temperature , , and . Effective film moduli for precrystallized (no laser treatment) and amorphous films are also included for reference. The asterisk denotes that laser treated specimen presented here have undergone CM, and thus nucleation and growth in order to solidify.
[(a) and (b)] temperature: representative AFM image from completely melted film. Note the presence of lateral growth, although not well defined or of significant length, .
Scanning electron micrographs, : [(a) and (b)] interior and boundary regions, respectively. Partially melted film characterized by small grain size limited to film thickness, : [(c) and (d)] interior and boundary regions, respectively. NCM regime characterized by bimodal grain size distribution, : [(e) and (f)] interior and boundary regions, respectively. Completely melted film characterized by the presence of large aspect ratio, well defined lateral growth, .
Average grain size as a function of % CMT. Note the evolution of grain size distribution as the energy density transitions through the PM, NCM, and CM regimes.
Article metrics loading...
Full text loading...