Effects of Annealing on Microstructure and Properties of Electroformed Nano-crystalline Ni-W Alloy

The nano-crystalline Ni-W alloy was prepared by electroforming method.And then the alloy was vacuum annealing treatment at 250 ℃～500 ℃ for 1 h.The microstructure and mechanical properties of the samples before and after annealing treatment were studied using LSCM,SEM,XRD and microhardness tester.The results indicate that the microstructure of the nano-crystalline Ni-18wt%W alloy is tending towards homogeneous with the increase of annealing temperature;the grain size of the alloy increases from 6.80 nm to 12.56 nm when the annealing temperature rise to 500 ℃;the harden phase Ni4W is precipitated after annealed at 300 ℃,400 ℃and 500 ℃;the microhardness of the alloy increases gradually after annealing at low temperatures and reaches the maximum at 300 ℃,then decreases with the increase of the annealing temperature.