The Preparation And Performance Research On High Entropy Alloy Binder Of Super Hard Abrasive Materials

As a special type of sawing tool in superhard material tools,ultra-thin cutting sheet,have some characteristics: the bonding agent needs to have high hardness,strength,thermal stability and low sintering temperature and other requirements.While the ordinary metal,ceramics,resins and other superhard tools bonding agent can’t meet these requirements.In this paper,as a bonding agent to ultra-hard material ultra-thin cutting sheets,the newly developed high-entropy alloys get some excellent performance,like high strength,high hardness,good wear resistance,high temperature oxidation resistance,etc.Through different metal elements and ratios,high entropy alloy binder powder obtained by the mechanical alloying method fully mix with diamond and cBN powder,and then use SPS discharge plasma to obtain a super-hard composite sintered body.Using XRD,DSC and SEM to analyze the microstructure and sintering temperature of the samples above,especially the binding state of matrix binder and superabrasive grit.And the hardness,flexural strength are measured by the mechanical property test method.Based on the results of the performance test,we choose suitable high entropy alloy binder for new superhard-material tool with high strength,high thermal stability and high grinding efficiency.A series of high entropy alloy binders including AlZnCuFeTi,AlFeNiCrCu,CoCrNiCuFe,CoCrNiFeMn,CoCrNiCuMn and CoCrNiCuFeMn turn into amorphous structure,BCC+FCC solid solution structure and FCC solid solution structure after melling for 30 h.It was found that after alloying for 30 h,AlZnCuFeTi,AlFeNiCrCu,CoCrNiCuFe,CoCrNiFeMn,CoCrNiCuMn and CoCrNiCuFeMn alloys were alloyed with amorphous phase,BCC+FCC solid solution structure,and FCC solid solution structure(CoCrNi series).After SPS sintering,the phase composition of the binder was changed from the amorphous state to the BCC structure except AlZnCuFeTi,and the other binders had the same phase composition,and all had the same phase composition as the powder state.After the composite sintering with a certain amount of diamond or cBN powder,the phase composition of the binder matrix does not change,but after the sintering temperature reaches 1000 °C and the superhard abrasive addition amount exceeds 20 vol.%,AlZnCuFeTi,AlFeNiCrCu are shown in XRD.TiC,TiN,AlN and other reactants appeared in the composite sintering process with diamond and cBN,and were detected as the reaction bonding layer between the matrix binder and the superhard abrasive particle in the SEM image and the corresponding EDS results.In the composite sintered body of AlZnCuFeTi,AlFeNiCrCu and diamond,the optimal diamond addition amounts of the two are 20 vol.% and 10 vol.%,respectively.The best sintering temperature for the composite sintered body is 900 °C and 1000 °C,respectively.In the composite sintered body of AlZnCuFeTi,AlFeNiCrCu and CoCrNiFeMn and cBN,the optimum cBN addition amounts of the three are 20 vol.%,10 vol.% and 10 vol.%,respectively,which corresponds to the optimum sintering temperature of the composite sintered body.900 °C,950 °C,and 1000 °C,respectively.The flexural strength of AlZnCuFeTi,AlFeNiCrCu and diamond composite sintered bodies is between 181.65 and 570.25 MPa,and 160.76~668.35 MPa.The flexural strengths of AlZnCuFeTi,AlFeNiCrCu and CoCrNiFeMn and cBN composite sintered bodies are 327.35~638.23 MPa and 127.21~841.12 MPa,respectively.Between 753.97 and 1526.90 MPa.Compared with AlFeNiCrCu,AlZnCuFeTi is more suitable for composite sintering with diamond.The CoCrNiFeMn has the highest flexural strength and the AlZnCuFeTi has the lowest bond with the cBN composite sintered binder,but the interfacial bonding state with the cBN is the best.