PROCESS FOR PREPARING A HIGH ENTROPY ALLOY AS POWDER, FOR PLASMA JET COATINGS AND ALLOY OBTAINED THEREBY

• Main Authors: GRIGORESCU CRISTINA EUGENIA ANA, DINU MIHAELA, IORDACHE ANA MARIA, ZOIŢA NICOLAE CĂTĂLIN, PANĂ IULIAN, KISS ADRIAN EMIL, RUSU MĂDĂLIN ION, CONSTANTIN LIDIA RUXANDRA, PÂRÂU ANCA CONSTANTINA
• Format: Patent
• Language: English; Romanian
• Published: 28.02.2024
• Subjects: ALLOYS; CASTING; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; MAKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; METALLURGY; PERFORMING OPERATIONS; POWDER METALLURGY; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WORKING METALLIC POWDER

The invention relates to a method of preparing high entropy alloys (HEA) as powder for plasma jet coatings and to thus obtained alloys. According to the invention, the method consists in weighing the powders of at least 5 main elements, with a granulation comprised between 200...325 mesh and a purity of 99.0...99.95%, with the ratio of the atomic concentrations comprised between 1.00/1.00/0.5/1.00/1.00...1.00/1.00/1.00/1.00 /1.00, the powders are mixed with a process control agent (PCA) in a percentage of 0,5...3% of the powder mixture mass and placed in a 250-ml vessel of a planetary ball mill, the vessel and the balls being made of ZrO2, WC or hardened steel, the balls, in number of 6...50, having a diameter between 10...30 mm, followed by purging the vessel for 5...10 min. with Ar flow, at a pressure between 1.05...1.3 bar, homogenization of the powder mixture with PCA by means of a planetary mill, with a speed of 100...150 rpm for 30...60 min., mechanically alloying the powder mixture by grinding in a ball mill, at a speed of 300...350 rpm for 20...35 hours of effective processing, in cycles of 5...7 min. and 2...4 minutes of rest, each cycle being performed with the direction of rotation reversed from the previous cycle, removal of PCA from the alloy powder by evaporation in the oven heated to 150...300°C, compaction of the powder as pellets in the mould, with the pressure of 200...350 MPa, sintering the pellets in ultra high vacuum for 60...120 min. at the temperature of 1000...1150°C and obtaining the powder of multicomponent material by grinding the sintered pellets in a planetary mill protected with Ar, at the speed of 200...300 rpm for 30...180 min. According to the invention, the alloys are of CrCoNiVCu and TiCrAl0.5NbY type, respectively, in powder form for plasma jet coatings in applications requiring materials with adjustable properties: hardness, wear and corrosion resistance, etc.