Corrosion Resistance And Mechanical Properties Of Zr-based Alloy After Laser Remelting

In this paper, Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5amorphous alloy was used. The effects oftreating by different laser power of the material’s macroscopic characteristics, corrosionresistance, mechanical properties was studied, and providing a certain amount oftheoretical knowledge for the surface modification of amorphous materials to promote theamorphous materials applications in industrial.The experimental results showed that: the remelting rate is far higher than the criticalcooling rate of the formation of the amorphous material, after laser surface remelting,there’s a clear three parts of melting zone, the heat-affected zone and the matrix in thesurface of the amorphous. After treated by900W laser remelting the heat-affected zone’swidth greater than that of the heat affected zone remelting by700W laser remelting, thereason was analyzed, they were closely related with the experienced thermal historyduring remelting; after remelting by900W the amorphous without any occurrence ofcrystallization, the elements of the amorphous have a more uniform distribution, there’salso no crystallization occurs after remelting by700W, elements distribution moreuniform, too, both in the heat affected zone have undergone significant crystallization.The corrosion resistance of the material after laser remelting was studied byelectrochemical polarization. By analysis the polarization curves of the remelting zone ofeach sample and the crystallized sample, reached the following conclusions, for their levelof corrosion resistance can be obtained in the following order, thermodynamics: E_900W>E_700W>Eunhandled> E_{700W crystallization}> Ecrystallization; dynamics perspective: I_crystallized> I_{700Wcrystallization}> I_unhandled> I_700W>. I_900WThrough the Nyquist diagram of each sample analysis,the quality of their corrosion resistance has the following sequence: R_z900W> R_{z unprocessed}>R_z700W crystallization. The immersion test also confirms the above conclusion that after a highpower laser remelted amorphous materials having improved the corrosion resistanceproperty, and their corrosion penetration depth of the order of B_{700W crystallization}>B_unhandled>B_900W, the corrosion penetration depth is much less than1, less than that of the traditionalcrystalline alloys, such as steel and other alloy materials.Finally, the nanoindentation study of the material’s mechanical properties after laser treatment was performed. After treated by laser remelting, the amorphous alloy surface’shardness decreased, the average of hardness after laser remelting by900W and700Wremelting annealing were reduced36.7%and32.5%compared with the matrix; the elasticmodulus lower than34.5%and31.8%of the matrix respectively; through900W laserremelting the friction coefficient of the material was similar to the substrate, but thefriction coefficient after remelting by700W and annealing increased almost doubled to thesubstrate, indicating reduced material wear.The above results suggest that the using of laser surface modification on amorphousmaterials is an effective method, but if we want to improve the corrosion resistanceperformance by little effect on its mechanical properties,the crystallization should beavoid.