Abstract
The structure of alloy films deposited by the electroless plating method continuously changed from the crystalline structure which formed an aggregation of microcrystals, to an amorphous structure depending on the concentration of B in the deposited films. In the present investigation, the lattice images of Ni–B alloy films with various concentrations of B, which were deposited by the electroless plating method using DMAB as a reducing agent, were observed by the use of TEM. In an electron diffraction pattern of a Ni film containing 5.5 at%B, both 111 and 200 Debye-Scherrer rings were diffused. In the observation of the lattice image of this film, it was discovered that this film consists of an aggregation of microcrystals 10 nm in diameter. The size of the microcrystals in the film containing 7.9 at%B was smaller than the film containing 5.5 at%B. Lattice fringes in this film were observed as curved line in all area, and the boundary of each grain was not clear. In an electron micrograph of a Ni–B alloy film containing 17.1 at%B, the amorphous structure was observed in almost all area, except in extremely small areas where some lattice fringes were observed. The authors termed the structure showing such a lattice image “amorphous-like structure” in recent reports. After the heat-treatment at a relatively high temperature, which is below the crystallization temperature of Ni3B, these alloy films were investigated for further detailed structures. In a film containing low B concentration, the lattice fringes grew with the grain growth, and in a film containing the highest B concentration, the lattice fringes were very small and few.
