Reactive Phase Formation in Sputter-Deposited Ni/Al Thin Films

1995 ◽  
Vol 382 ◽  
Author(s):  
K. Barmak ◽  
C. Michaelsen ◽  
R. Bormann ◽  
G. Lucadamo

ABSTRACTWe have investigated reactive phase formation in magnetron sputter-deposited Ni/Al multilayer thin films with a 3:1 molar ratio and periodicities ranging from 2.5-320 nm. In addition, we studied the transformation of a codeposited film of the same composition. We find that an amorphous phase has already formed during deposition, and that the extentof formation of this phase increases with decreasing periodicity. The first crystalline phase then nucleates from this amorphous phase upon annealing. The formation of the amorphous phase considerably reduces the driving force and explains why during subsequent reactions nucleation kinetics become important. We obtain Ni2Al9 as the first product phase during heat treatment in some cases before NiAl3 occurs. For films with modulation periods larger than 40 nm, formation of NiAI3 is a two stage process as reported earlier, with the first stage being due to nucleation and growth to coalescence of NiAl3 grains, and the second stage being the growth of NiA13 normal to the initial interface until the reactant phases are consumed.

1997 ◽  
Vol 12 (1) ◽  
pp. 133-146 ◽  
Author(s):  
K. Barmak ◽  
C. Michaelsen ◽  
G. Lucadamo

We have investigated reactive phase formation in magnetron sputter-deposited NiyAl multilayer films with a 1 : 3 molar ratio and various periodicities, L, ranging from 320 nm down to a codeposited film with zero effective periodicity. The films were studied by x-ray diffraction, differential scanning calorimetry, electrical resistance measurements, and transmission electron microscopy. We find that Ni and Al have reacted during deposition to form the B2 NiAl phase and an amorphous phase. The formation of these phases substantially reduces the driving force for subsequent reactions and explains why nucleation kinetics become important for these reactions. Depending on the periodicity, these reactions result in the formation of NiAl3 or Ni2Al9 followed by NiAl3. Detailed calorimetric analysis reveals differences in the nucleation and growth behavior of NiAl3 compared with other studies.


Author(s):  
G. Lucadamo ◽  
K. Barmak ◽  
C. Michaelsen

The subject of reactive phase formation in multilayer thin films of varying periodicity has stimulated much research over the past few years. Recent studies have sought to understand the reactions that occur during the annealing of Ni/Al multilayers. Dark field imaging from transmission electron microscopy (TEM) studies in conjunction with in situ x-ray diffraction measurements, and calorimetry experiments (isothermal and constant heating rate), have yielded new insights into the sequence of phases that occur during annealing and the evolution of their microstructure.In this paper we report on reactive phase formation in sputter-deposited lNi:3Al multilayer thin films with a periodicity A (the combined thickness of an aluminum and nickel layer) from 2.5 to 320 nm. A cross-sectional TEM micrograph of an as-deposited film with a periodicity of 10 nm is shown in figure 1. This image shows diffraction contrast from the Ni grains and occasionally from the Al grains in their respective layers.


2002 ◽  
Vol 91 (12) ◽  
pp. 9575 ◽  
Author(s):  
G. Lucadamo ◽  
K. Barmak ◽  
C. Lavoie ◽  
C. Cabral ◽  
C. Michaelsen

1995 ◽  
Vol 398 ◽  
Author(s):  
G. Lucadamo ◽  
K. Barmak ◽  
C. Michaelsen

ABSTRACTWe have investigated reactive phase formation in magnetron sputter-deposited Ni/Al multilayer films with a 1:3 molar ratio and various periodicities ranging from 320 nm to a codeposited film with an effective periodicity of zero. The films were studied by x-ray diffraction, differential scanning calorimetry, electrical resistance measurements, and transmission electron microscopy. We find that a reaction which results in the formation of an amorphous phase has taken place during the multilayer deposition process. This reaction substantially reduces the driving force for subsequent reactions and explains why nucleation kinetics become important for these reactions. The mode of transformation for a film with 10 nm periodicity was investigated, in detail, by applying the Johnson-Mehl-Avrami analysis to data obtained from isothermal and constant heating rate differential scanning calorimetry, in combination with electron microscopy studies of the transformation microstructure.


Author(s):  
F. Ma ◽  
S. Vivekanand ◽  
K. Barmak ◽  
C. Michaelsen

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.


JOM ◽  
2021 ◽  
Author(s):  
Evgeny T. Moiseenko ◽  
Sergey M. Zharkov ◽  
Roman R. Altunin ◽  
Oleg V. Belousov ◽  
Leonid A. Solovyov ◽  
...  

2002 ◽  
Vol 92 (1) ◽  
pp. 310-319 ◽  
Author(s):  
David L. Young ◽  
Helio Moutinho ◽  
Yanfa Yan ◽  
Timothy J. Coutts

1989 ◽  
Vol 8 (12) ◽  
pp. 1393-1394 ◽  
Author(s):  
Masahiro Kitada ◽  
Noboru Shimizu ◽  
Teruho Shimotsu

1995 ◽  
Vol 403 ◽  
Author(s):  
K. Barmak ◽  
C. Michaelsent ◽  
J. Rickman ◽  
M. Dahmstt

AbstractIt is a well known fact that the properties and performance of polycrystalline materials, including polycrystalline thin films, are strongly affected by the grain structure. Therefore, in treating reactive phase formation in these films, it is (or it will inevitably be) necessary to quantify the grain structure of reactant and product phases and its evolution during the course of the reaction. Theoretical models and the conventional view of thin film reactions, however, have been largely extensions, to small and finite dimensions, of theories and descriptions developed for bulk diffusion couples. These models and descriptions primarily focus on the growth stage and to a much lesser extent on the nucleation stage. Consequently, these models and descriptions are not able to treat the development of product phase grain structure. Recent calorimetric investigations of several thin film systems demonstrate the importance of nucleation kinetics (and hence nucleation barriers) in product phase formation and provide quantitative measures of the thermodynamics and kinetics of formation of the product phases, thereby allowing some degree of comparison with reaction models. Furthermore, microstructural investigations of thin-film reactions demonstrate the non-planarity of the growth front and highlight the role of reactant-phase grain boundaries. In this paper, a summary of these experimental studies and recent theoretical treatments, which combine nucleation and growth in an integrated manner, is presented, with particular emphasis on the Nb/Al system. These experiments and models lead to a new view of reactive phase formation and grain structure evolution as one in which the latter is an integral part of the former. Based on this view, directions for future research are discussed.


Sign in / Sign up

Export Citation Format

Share Document