合金化效应对Ni-W镀层力学性能的影响

Effect of Microalloying Addition on Mechanical Properties of Ni-W Coating

摘要:

本文通过研究微量合金元素W添加（< 2.0 at.%）对电沉积Ni-W镀层表面形貌、微观组织和力学性能的影响，探索了材料制备工艺与微合金化对改善Ni-W镀层组织、进一步提高力学性能的内在机制。结果表明，Ni-W镀层为单相FCC结构，随着W含量的增加，镀层表面形貌从粗大的棱锥界面沟槽转变为均匀分布的微孔，同时表面粗糙度和晶粒尺寸逐渐减小，且镀层中Ni(220)衍射峰的强度也逐渐减弱；而镀层的屈服强度在1.0 at.%W含量左右发生突增，从~1.0 GPa增长到~2.0 GPa，拉伸延伸率却没有明显变化。此外，Ni-W镀层具有比较稳定的应变硬化能力，基本不随合金元素含量而变化。本文通过微合金化对表面形貌和微观组织的调控，实现了低W含量Ni-W合金镀层的力学性能优化。

Abstract:

This manuscript focused on the effect of processing technology and microalloying addition on the microstructure and mechanical properties of Ni-W coatings that were prepared by electrodeposition. For this reason, the surface morphology, microstructure, and tensile properties of Ni-W coatings were studied within a small W addition of less than 2.0 at.%. The experimental results showed that the Ni-W coatings have a single-phase FCC structure. By increasing the W content, the surface morphology of the coatings varied from the grooves between the coarse pyramid structures to uniformly distributed micropores. At the same time, the intensity of Ni(220) diffraction peak of the coatings also gradually weakened, with the surface roughness and the grain size reduced. There was a critical W addition of about 1.0 at.%, where the yield strength of Ni-W coating increased from ~ 1.0 GPa at the W addition regime <1.0 at.% sharply to ~ 2.0 GPa at the W addition regime >1.0 at.%. However, the tensile elongation was insensitive to the W content, which kept almost unchanged within the studied W addition range. In addition, strain hardening capacity of the coatings was also stable with the W content. In this work, the mechanical properties of Ni-W coating with micro-addition of W were optimized through manipulation of microalloying effect on the surface morphology and microstructure.