The T values obtained for the as quenched ribbons
The plating bath composition and electroplating conditions are given in Table?1. The plating bath for Ni–W alloys is an aqueous solution of nickel sulfate and sodium tungstate with citric BIIE 0246 and ammonium sulfate as complexing agents. Electrodeposition is conducted on a Cu substrate that is formed into dumbbell shaped specimens by UV lithographic techniques with Ir–Ta mesh as the anode . The electrodeposited Ni–W alloys were separated from the Cu substrate by immersing the samples in an aqueous solution containing CrO3 and H2SO4. Fig.?1 shows a schematic illustration of the Ni–W electrodeposition apparatus. The interval between cathode plate and anode plate is 150 mm. The polyester agitation rod (18 mm diameter, 150 mm long) is used to brush the film surface. The distance from the Cu substrate to the center of the agitation rod is approximately 9 mm, so that the Cu substrate and agitation rod are in intimate contact during electrodeposition. Agitation by the brushing technique was conducted at a rate of 40 rpm with a sliding distance of 260 mm. Structural analysis of the electrodeposits was performed using high resolution transmission electron microscopy (HR-TEM; JEOL JEM-2010) at an accelerating voltage of 200 kV, and X-ray diffraction (XRD; Rigaku Smart Lab) with Cu Kα radiation. By the results of the XRD measurement in our previous work , only Ni (1 1 1) peak were shown at the angle of 43 degree in electrodeposited Ni–W alloys. In this study, only (1 1 1) peak was observed. Grain sizes were estimated from dark-field HR-TEM images and by application the Scherrer equation to the Ni (1 1 1) peak of the XRD profiles. W contents for the Ni–W alloys were determined by electron probe microanalysis (EPMA; JEOL JXA-8900R) at an accelerating voltage of 15 kV, and with ZAF correction applied to the EPMA spectra. Tensile tests were performed using a micro strain tester (Shimadzu MST-I) with a initial strain rate of 4.2 × 10−4 s−1 at room temperature. The strain was measured using a strain gauge. The tensile specimen size was 0.5 mm wide, a 4 mm gauge length and 20–23 μm thick. The mesoscale surface structures of the Ni–W films were observed using scanning electron microscopy (SEM; JEOL JSM6500F) at an accelerating voltage of 15 kV. The surface roughness and surface defects of the Ni–W films were observed using confocal laser scanning microscopy (Olympus OLS-3000).