Study On High Temperature Oxidation Resistance And Corrosion Resistance Of The AlTiNiCuCo_x High Entropy Alloy

High-entropy alloy is composed of five or more elements.It breaks the design concept of traditional alloys.Because of its unique organization structure,it has excellent properties,such as high strength,hardness,certain friction and wear resistance,corrosion resistance and high temperature oxidation resistance and so on.Current research shows that it has potential application prospects in high temperature oxidation resistance and chemical corrosion resistance.The main purpose of this research is to obtain a high-entropy alloy with good high temperature oxidation resistance and chemical corrosion resistance.According to the alloying principle of metals,the alloy that consists of Al、Ti、Ni、Cu、Co were designed,AlTiNiCuCo_X(_X=0.5;0.75;1.0;1.25;1.5)high entropy alloy was prepared by vacuum induction melting furnace.The microstructure and phase composition of as-cast AlTiNiCuCo_x high-entropy alloy were analyzed by metallographic microscope,scanning electron microscope,scanning energy spectrum analyzer and X-ray diffractometer.The hardness,friction and wear resistance,high temperature oxidation resistance and chemical corrosion resistance of high entropy alloy of this system were studied and analyzed by means of microhardness tester,high temperature friction and wear tester,box-type resistance furnace and electrochemical workstation.The effect of Co content on the structure and properties of high entropy alloy of this system was investigated.Among them,the high temperature oxidation resistance and corrosion resistance of AlTiNiCuCo_X high entropy alloy at different temperatures were mainly analyzed.The analysis shows that the morphology and phase composition of the alloy will change with the change of Co content.With the increase of Co content,dendrites gradually change from massive to dendritic,and the shape is more and more regular,and the structure contrast is more and more obvious.When the Co content is 1,the alloy consists of FCC phase and BCC phase,and there is no impurity.In the interdendrite of AlTiNiCuCo_X high entropy alloy,there is Cu rich solid solution,and there are a large number of Al,Ti,Ni and Co elements in the dendrite,which are uniformly distributed.The experimental results show that high entropy alloys of this system have high hardness,and hardness varies with Co content.When the content of Co is 1,the hardness reaches the maximum.The hardness of dendrite is higher than that of whole alloy and higher than that of interdendrite.The high entropy alloys of this system possess good friction and wear resistance at room temperature,and AlTiNiCuCo high entropy alloy has better friction and wear resistance than others.At high temperatures,the friction and wear resistance of AlTiNiCuCo high entropy alloy increases with the increase of temperature,but it is not as good as that of AlTiNiCuCo high entropy alloy at room temperature.The high entropy alloys of this system have high temperature oxidation resistance at 800°C、900°C.AlTiNiCuCo high entropy alloy does not possess high temperature oxidation resistance at 1000°C.The high entropy alloys of this system possess certain chemical corrosion resistance in acidic,alkaline and neutral solutions,among which is the best in the alkaline corrosion solution.AlTiNiCuCo high entropy alloy has the best chemical corrosion resistance.