グルコン酸浴による電析バルクナノ結晶Ni-Mo合金の作製と機械的性質

Abstract

To produce bulk nanocrystalline Ni-Mo alloys with high plasticity, we developed Ni-Mo alloy electrodeposition processes showing high current efficiency and causing no micro-crack occurrence on electrodeposits. Electrodeposition was conducted using electrolytes consisting primarily of nickel sulfamate and sodium molybdate, with sodium gluconate. Using sodium gluconate and applying current density of 20-30 mA/cm2 improved the current efficiency to approximately 90%, efficiently producing a bulk 1mm thicksample. For Mo contents of 0.7-2.9 at%, the electrodeposited alloys have a nano-crystalline structure with 14-37 nm grain sizes, which are dependent on the Mo content. The Ni-2 at%Mo alloy with grain size of 16 nm exhibited high hardness of 5.2 GPa and tensile strength of 1.4 GPa. However, the electrodeposited bulk nanocrystalline Ni-Mo alloys showed fracture in the elastic region. Present results and discussion show that low deformability was related to the high microstrain values and high impurity contents of electrodeposited Ni-Mo alloys. This study, which developed a high efficiency Ni-Mo alloy electrodeposition system, is expected to direct future work in this field.