Electrodeposition of Invar Fe-Ni Alloy/SiC Particle Composite

Abstract

We fabricated electrodeposited Invar Fe-Ni alloy/SiC composites and assessed their hardness properties. Using the composite plating method with SiC particles of 0.5 µm diameter, we achieved Invar Fe-Ni alloy/SiC composites with SiC at concentrations as high as 22.4 vol%. The co-deposition of SiC particles into the Invar Fe-Ni alloy suppressed the decrease in hardness of the composites after annealing at 600°C for reducing its CTE, and the hardness of the composites was greater than that of the electrodeposited Invar alloys with annealing and pyrometallurgically produced Invar alloys. Consequently, the 600°C annealing of the electrodeposited Invar Fe-Ni alloy/SiC composites with SiC (20 vol% or more) afforded Invar/SiC composites with a high degree of hardness of approximately 200 HV and a low CTE of approximately 1-2 ppm/°C. These composite films can be used in the fabrication of MEMS elements that require high mechanical strength and high thermal dimensional stability.