| CHENG Yifan,LI Fengguang,LIAO Luhai,LIU Jianyong,YANG Wei,DUN Yapeng.Microstructure and Properties of AlCoCrFeNi High-entropy Alloy Laser Cladding on TC4 Titanium Alloy Surface[J],54(9):189-203 |
| Microstructure and Properties of AlCoCrFeNi High-entropy Alloy Laser Cladding on TC4 Titanium Alloy Surface |
| Received:September 20, 2024 Revised:December 30, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.09.016 |
| KeyWord:TC4 titanium alloy laser cladding high-entropy alloy microstructure transformation high temperature oxidation resistance wear resistance |
| Author | Institution |
| CHENG Yifan |
School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan , China |
| LI Fengguang |
School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan , China |
| LIAO Luhai |
School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan , China |
| LIU Jianyong |
School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan , China |
| YANG Wei |
School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan , China |
| DUN Yapeng |
School of Materials Science and Engineering, Hubei University of Automotive Technology, Hubei Shiyan , China |
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| Abstract: |
| The disadvantages of titanium alloys such as poor resistance to high temperature oxidation, low hardness and poor wear resistance limit the use of titanium alloys in practical applications, and surface modification techniques can be considered to improve the surface properties of titanium alloys. In this paper, the microstructure and properties of AlCoCrFeNi high-entropy alloy cladding layer laser melted on TC4 titanium alloy surface are investigated, and high-temperature oxidation resistance test, hardness test and abrasion resistance test are carried out on the cladding layer and the substrate, and the specimens are observed by test methods such as OM, SEM, EDS and XRD, to analyze the microstructure evolution law of the high-entropy alloy cladding layer in the process of laser cladding and the improvement of the properties of the cladding layer on the TC4 substrate. The experimental results show that the best cladding effect is achieved when the laser process parameters are 1 400 W and 12 mm/s, and the AlCoCrFeNi high-entropy alloy cladding layer forms a good metallurgical bond with the TC4 substrate. The cladding layer is mainly composed of FCC and BCC phases, in which the BCC phase 1 is an AlNi2Ti phase and the BCC phase 2 is a CrFe phase, and the phase composition of the TC4 substrate is α-Ti and β-Ti. The SEM and EDS results can clearly show the microstructure transformation law in the process of fusion cladding, and from the combination of the cladding layer and the substrate upward. There is a heat-affected zone, a planar crystal zone, a columnar crystal zone, and an equiaxial crystal zone. The formation of microstructures in each region is controlled by the temperature gradient (G) and the crystal growth rate (R), and the G/R value is an important criterion for controlling the growth pattern of crystals. The magnitude of heat input also affects the growth of equiaxial crystals and columnar crystals. Under the condition of 800 ℃, the oxidized surface morphology of AlCoCrFeNi cladding layer is good, and no obvious oxide skin is formed, while the surface of the TC4 substrate has already appeared a thicker oxide film and some of them have been cracked off; The oxidized weight gain rate of the TC4 substrate and the AlCoCrFeNi cladding layer is 28.546 mg/cm2 and 1.318 mg/cm2, respectively. And the oxides on the surface of high-entropy alloy are mainly Al2O3, TiO2 and (Cr,Fe)2O3, and the oxides on the surface of the TC4 substrate are mainly TiO2 and Al2O3. The oxide film of the AlCoCrFeNi alloy cladding layer is very thin, with a thickness of less than 1 μm, but the TC4 surface forms an oxide film of more than 100 μm. The average hardness of the cladding layer is 1.95 times of the average hardness of the substrate, which reaches 677.0HV. At room temperature, the coefficients of friction of the TC4 substrate and AlCoCrFeNi cladding layer are 0.398 and 0.473, respectively, but TC4 has more relative wear. The laser cladding of AlCoCrFeNi high-entropy alloy on the surface of TC4 titanium alloy significantly enhances the high-temperature oxidation resistance, hardness and wear resistance of the TC4 titanium alloy substrate. |
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