Anisothermal solid-state reactions of Ni/Al nanometric multilayers

• Type: Article in International Scientific Journal
• Date: 2011

Authors

Simoes, S (Author) FEUP; Viana, F (Author) FEUP; Ramos, AS (Author) Other; Vieira, MT (Author) Other; Vieira, MF (Author) FEUP

Journal

Title: Intermetallics

Vol. 19

Pages: 350-356

ISSN: 0966-9795

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 46 Citations

ISI Web of Science

Scopus - 48 Citations

Scientific classification

CORDIS: Technological sciences > Engineering > Materials engineering

FOS: Engineering and technology > Materials engineering

Other information

Authenticus ID: P-002-TS6

DOI: 10.1016/j.intermet.2010.10.021

Abstract (EN): The structural evolution of Ni/Al multilayer thin films with temperature was studied by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and X-ray diffraction (XRD). Thin films with nanometric Ni and Al alternated layers were deposited by d.c. magnetron sputtering. In our experiments, we used a bilayer thickness of 5, 14 and 30 nm and a total film thickness ranging from 2 to 2.7 mu m. The XRD patterns of the as-deposited sample revealed only peaks of Al and Ni. DSC experiments were performed on freestanding films, from room temperature to 700 degrees C at 10 and 40 degrees C/min. Two exothermic reactions were detected in the DSC curves of the film with a 30 nm bilayer thickness, with peak temperatures at 230 and 330 degrees C. The films with 5 and 14 nm bilayer thickness presented only one exothermic peak at 190 and 250 degrees C, respectively. To identify the intermetallic reaction products, DSC samples were examined by XRD. NiAl formation corresponds to one single DSC peak, for films with short bilayer thicknesses (5 and 14 nm). The films with 30 nm bilayer thickness were heated at 250 degrees C (T = T(1st) (peak)). 300 degrees C (T(1st) (peak) < T < T(2nd) (peak)), 450 degrees C (T > T(2nd) (peak)) and 700 degrees C. The XRD results indicated that at 250 degrees C the phase formed was NiAl(3), whilst NiAl(3) and Ni(2)Al(3) phases were identified at 300 degrees C. For the 450 degrees C sample, only NiAl was detected. Further heating to 700 degrees C promotes the growth of NiAl grains.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7