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The laser remelting technique was applied to the surface modification of the Al0.65CoCrFeNi high-entropy alloy (HEA) to further advance its mechanical potential. The microstructure of the remelted layer was refined from coarse dendritic to submicron-scale basket weave compared with the as-cast substrate, resulting in a 1.8-time increase in Vickers microhardness. The nanoindentation tests indicated that the nanohardness of the remelted layer was higher than that of each phase in the substrate. Meanwhile, the remelted layer retained considerable plasticity, as evidenced by its high Wp/Wt ratio (0.763) and strain hardening exponent (0.302). Additionally, adhesive wear prevailed on the substrate, while only abrasive wear features were observed on the remelted layer. Accordingly, the average friction coefficient and the wear rate of the remelted layer were minimized by 23% and 80%, respectively, compared with the substrate. Our findings explored an industrialized method to enhance the surface properties of the Al0.65CoCrFeNi HEA and also provided some helpful references for its laser additive manufacturing.

Three dichloroacetate derivatives of hydroxyanthraquinone were synthesized. NMR studies showed that only monoesterified derivative compound 1 had a tautomerization. Since monoetherified derivative of hydroxyanthraquinone did not show tautomerization, a hypothesis that nucleophilicity played an important role in the tautomerization was proposed. The molecular structures of monoesterified derivative compound 1 and diesterified derivative compound 2 were calculated by using DFT method, and the result showed that the electronic density of carbonyl at 9-position of compound 1 was much larger than that of compound 2, which indicated that the hypothesis mentioned above was reasonable.