Research On Laser High Entropy Alloying On The Surface Of Single-element Cu Base Alloy

High entropy alloys are developed in the1990s with a variety of major elements(component number n≥5) and showing a simple solid solution phase alloy body-centeredcubic structure and face-centered cubic structure, with a high hardness, high strength, goodwear resistance, corrosion resistance, excellent oxidation resistance and so on, has beenapplied to molds, cutting tools, motors, ships, etc. Laser cladding can be achieved in alow-cost metal surface, preparation of high-performance coatings. In this study, high entropyalloys coating on copper by Nd:YAG solid pulse laser, semiconductor, CO2, fibber laser canimprove the properties of the substrate, and study the influence of laser parameters on thequality of high entropy alloys, microstructure and hardness. Optical microscopy, scanningelectron microscopy, micro hardness tester, and X-ray diffraction are used to analyze thesubstrate surface alloyed layer morphology, composition and phase structure analysisrespectively, determining the optimum laser high entropy alloying method and electionpreparation process the excellent performance of the noble metal layer.The test results showed that in situ synthesis FeCoCrAl quaternary alloy is composed oftwo intermetallic compounds and BCC, FeCoCrAl/Cu high entropy alloy layer on the surfaceof Cu substrate can be obtained by laser cladding with FeCoCrAl alloy powder, and hassimple solid solution structure. With the laser current increases, organized by granulargradually transformed into cellular. Through thermodynamic calculation, FeCoCrAl/Cu highentropy alloy layer conforms to generate solid solution condition. The effect of the grainrefinement and solid solution strengthening made the hardness of alloy layer higher thansubstrate significantly.FeCoCrAlNix/Cu high entropy alloy cladding prepared by semiconductor, CO2laser, andfiber alloying shows that, with the additions of Ni, composed of FCC and BCC graduallytransformed into a single FCC phase, and the hardness decreased. High entropy alloy with Mo,Ti elements additions respectively are composed of simple solid solution phase and otherphases. FeCoCrAlSi0.5/Cu with simple solid solution has good formability.The wear experiments show that the Cu substrate surface exhibits a mass loss, severeplastic deformation. When x changes from0to1.5, the regularity of wear is not same as hardness, due to meridian shaped organizations exist, FeCoCrAlNi/Cu alloying layer has thebetter wear resistance. The wear surface of FeCoCrAlSi0.5/Cu alloy layer is still smooth and noobvious adhesion, and appears only a small amount of black particles, smaller amount of wear.Because of the different laser power density and the laser absorption of various materialswith different wavelengths, alloying layers prepared with different lasers have differentmicrostructure. By calculating, the laser absorption rate of materials and the laser energydensity in the process of alloying shows: CO2laser＜fiber laser＜semiconductor laser.Combination with the actual situation of the organization, performance, preparation of sampleand equipment, high entropy alloying layer is easier formed on the Cu substrate surface byfiber laser.