Design and characterization of in-situ TiB reinforced TiB/Ti50Zr25Al15Cu10 non-equiatomic medium-entropy alloy composite coating on magnesium alloy by laser cladding.

[Display omitted] • TiB/Ti 50 Zr 25 Al 15 Cu 10 medium-entropy alloy composite coating (MEACC) was successfully prepared on the surface of magnesium alloy by laser cladding. • La rare earth element was added into the self-designed Ti 50 Zr 25 Al 15 Cu 10 non-equiatomic medium-entropy alloy in the form of LaB 6. • The strengthening mechanism with LaB 6 addition was investigated. • The corrosion and wear resistance of magnesium alloy got huge improvement. The improvement of corrosion resistance and wear resistance levels is of great significance because of the far-ranging impacts of them on the further application of magnesium alloys. In this work, a novel TiB/Ti 50 Zr 25 Al 15 Cu 10 medium-entropy alloy composite coating (MEACC) was successfully prepared on the surface of magnesium alloy by laser cladding. The effect of LaB 6 content on microstructure, micro-hardness, wear resistance and corrosion resistance of Ti 50 Zr 25 Al 15 Cu 10 coatings was studied in detail. The results show that TiB/Ti 50 Zr 25 Al 15 Cu 10 MEACCs are mainly composed of α-Ti, BCC and TiB phases. With LaB 6 content increased, the microstructure of the coating is refined and homogenized. And when the addition amount is excessive, Cu 2 La clusters appear. The lattice distortion caused by La3+ with large ion radius leading to the formation of hard BCC solid solution, as well as the dispersion strengthening of TiB in-situ, the coating presents high micro-hardness and excellent wear resistance. Especially, the average micro-hardness values of Ti 50 Zr 25 Al 15 Cu 10 coating with 4 wt% LaB 6 is ∼679.4 HV 0.3 , which is about 11 times than that of the substrate (∼61.6 HV 0.3). Besides, TiB/Ti 50 Zr 25 Al 15 Cu 10 MEACC displays excellent corrosion resistance. The minimum corrosion current density is 8.52 × 10−7 A·cm−2, and the oxidation phenomenon emerged in the coating. The oxide film is mainly composed of the oxidation state of Ti, Zr, Al, Cu and the sub-oxide state of Cu. [ABSTRACT FROM AUTHOR]