Rare Earth Effects on Adhesion of Cr_2O_3 Oxide Scale Formed on Surface of Co-40Cr Alloy

Isothermal and cyclic oxidation behaviors of Co 40Cr alloy at 1000 ℃ in air were studied. Scanning electron microscopy (SEM) was used to examine the oxide scale formed on the surface of the alloy. By comparing the oxidation behaviors of Co 40Cr alloy and its 3×10 16 and 3×10 17 Y +/cm 2 implanted specimens, it was found that the resistant to oxidation property of Co 40Cr was greatly improved due to the implantation of yttrium. Acoustic emission was used to study the distribution of defects at the interface between the scale and alloy. Raman spectrum was also used to study the stress status in chromic scale formed on the surface of Co 40Cr with and without yttrium. The main reason for the improvement of resistant to oxidation property of Y doped Co 40Cr probably is that yttrium can segregate to Cr 2O 3 grain boundaries and change the scale′s growing mechanism and mechanical property. Most importantly, Y implantation decreases the size and number of interfacial defects and the residual stress in the scale, and remarkably enhances the adhesion of chromia scale with Co 40Cr substrate.