2017 年 58 巻 7 号 p. 1038-1041
In this study, we fabricated bulk nanocrystalline Ni–W–B alloys by electrodeposition, using trimethylamine-borane (TMAB) as a boron source, showing how B doping affects tensile properties. In electrodeposition, the TMAB concentration was varied from 0 to 5.0 g/L. Adding TMAB to the deposition bath increased the B content of the electrodeposited alloys up to 0.36 at%, but did not significantly change the W content or grain size. Adding more TMAB than 0.1 g/L drastically decreased the material's tensile elongation. Cross-sectional hardness tests on alloys with poor ductility revealed non-uniform hardness and that the initial layer had a high hardness of 6.3–8.7 GPa. This result indicated that the TMAB had immediately decomposed and that the boron decomposition product was mixed into the initial electrodeposited layer. In contrast, the alloys electrodeposited with 0.01–0.05 g/L TMAB showed good tensile elongation of 11%. Our results reveal the appropriate amount of added TMAB in order to produce electrodeposited bulk samples with good ductility.
