Joyce C. Liu

Kinetics of NiAl3 and Ni2Al3 phase growth on lateral diffusion couples

The phase formation of NiAl3 and Ni2Al3 is studied on lateral diffusion couples of an Al‐rich source on a Ni thin film at temperatures from 375 to 500 °C. Analytical electron microscopy is used to determine the crystal structures, chemical compositions, and the widths of growing phases. Simultaneous growth of NiAl3 and Ni2Al3 is observed at 375 and 450 °C. Al atoms dominate the diffusion process in NiAl3 and Ni2Al3. The growth of Ni2Al3 has a parabolic dependence on annealing time, and the growth constant, X2/t, has an activation energy of 2.0±0.2 eV. The growth kinetics is further studied by comparing the growth rates of NiAl3 in one‐ and two‐phase growth, and by applying the criteria proposed by Gosele and Tu to the simultaneous growth of NiAl3 and Ni2Al3.

Phase formation of NiAl3 on lateral diffusion couples

The kinetics of NiAl3 phase growth is studied on lateral diffusion couples in the temperature range from 375 to 450 °C. The lateral diffusion couple consists of an Al‐rich source on a Ni2 Al3 thin film. Analytical electron microscopy is used to determine the crystal structures and chemical compositions of the growing phases. The results show that: (1) Al is the dominant moving species in the growing NiAl3 phase; (2) an equilibrium concentration of Al is established during the growth; and (3) the growth has a parabolic dependence on the annealing time. The study of NiAl3 growth kinetics on lateral diffusion couples bridges the gap between bulk and thin‐film diffusion couples in terms of reaction temperatures. The activation energy of NiAl3 growth is 1.2±0.2 eV.

Ion irradiation induced grain growth in Ni polycrystalline thin films

Ion irradiation induced grain growth in Ni polycrystalline thin films has been studied by transmission electron microscopy. At room temperature, irradiations were carried out with 240 keV Ar, 150–580 keV Kr and 560 keV Xe ions over a wide range of doses. A homogeneous grain growth from 9 to 40 run was observed after irradiations. Initially, the dimension of grains increases with the irradiation dose and the growth saturates in the high dose region. The dimension of a damaged volume generated by a single collision cascade determines the growth rate and the saturated grain size. Elevated temperature irradiations and annealing were performed to compare different mechanisms of grain growth. Samples irradiated with 1015 Kr/cm2 at 200°C show uniformly enlarged grains, comparing to the non-uniform grain growth on the thermally annealed samples. The absence of inhibition of grain growth for the irradiated samples leads to homogeneous grain growth.

Temperature effect on ion‐irradiation‐induced grain growth in Cu thin films

The average grain size in Ar+‐irradiated Cu films at room temperature increases with ion dose, following a relationship of d3.3−d3.30 =Kφ. For Ar+ and Xe++ irradiations, the grain growth kinetics are independent of temperature at T≤−60 °C and increase with temperature in the range from −60 to 102 °C. The activation energy of the temperature‐dependent contribution to grain boundary migration is about 0.14 eV, and the growth rate is independent of ion flux, suggesting that the ion‐irradiation‐induced grain growth is associated with the thermal spike diffusion.The average grain size in Ar+‐irradiated Cu films at room temperature increases with ion dose, following a relationship of d3.3−d3.30 =Kφ. For Ar+ and Xe++ irradiations, the grain growth kinetics are independent of temperature at T≤−60 °C and increase with temperature in the range from −60 to 102 °C. The activation energy of the temperature‐dependent contribution to grain boundary migration is about 0.14 eV, and the growth rate is independent of ion flux, suggesting that the ion‐irradiation‐induced grain growth is associated with the thermal spike diffusion.

Phase formation of NiAl/sub 3/ on lateral diffusion couples

The kinetics of NiAl3 phase growth is studied on lateral diffusion couples in the temperature range from 375 to 450 °C. The lateral diffusion couple consists of an Al‐rich source on a Ni2 Al3 thin film. Analytical electron microscopy is used to determine the crystal structures and chemical compositions of the growing phases. The results show that: (1) Al is the dominant moving species in the growing NiAl3 phase; (2) an equilibrium concentration of Al is established during the growth; and (3) the growth has a parabolic dependence on the annealing time. The study of NiAl3 growth kinetics on lateral diffusion couples bridges the gap between bulk and thin‐film diffusion couples in terms of reaction temperatures. The activation energy of NiAl3 growth is 1.2±0.2 eV.

Ar+ ion irradiation induced grain growth in Au and Pt thin films

Abstract A comparative study of Ar ion irradiation induced grain growth in Au and Pt thin films (40 nm) has been conducted by transmission electron microscopy. The grain growth rate in Au is about 3.5 times greater than that in Pt films. The saturated grain size in Au film is approximately 130 nm, more than 3 times larger than its film thickness, while the saturated grain size in Pt film is comparable to its film thickness. No secondary grains emerge after irradiation and post-annealing, in contrast with the secondary grain growth in thermally annealed Au and Pt films. Analogous to thermally-induced grain growth, the differences in the growth rates for the irradiated Au and Pt films can be modeled as differences in atomic mobility.

In Situ Hvem Study of Ion Irradiation-Induced Grain Growth in Au Thin Films

In situ observations of 1.5 MeV Xe/sup +/ ion irradiated Au films at room temperature and at 150/degree/C reveal the evolution of grain growth: the average grain size increases by the mechanisms of grain boundary migration and grain coalescence. 10 refs., 4 figs.