Effect Of Yttrium And TiC On Microstructure And Mechanical Properties Of AlCrFeNiCo Higu-entropy Alloy System

In this paper, the influece of Y on microstructure and mechanical properties of AlCrFeNiCo high-entropy alloy system were analyzed. AlCrFeNiCo and AlCrFeNiCoTi_0.5 were chosen as matrix alloy which have good mechanical properties.The AlCrFeNiCo-based in situ TiC particle reinforced AlCrFeNiCo matrix composite were prepared by NCAM in this paper. The reinforced-phase was TiC particle with high hardness and high thermodynamic stability. Then this paper researched the effect of solidification rate on the microstructure and mechanical properties of AlCrFeNiCo-TiC composites formed in situ, and exploring the method of preparing new matrix composite which have well comprehensive properties.The microstructures and phase structures were systematically investigated by OM, SEM, EDS, and XRD. Furthermore, the macrohardness, compression properties, abrasion resistance were also tested and analyzed.The analysis showed that,with the addition of Y element, dendrite structure was found in AlCrFeNiCo alloy ,which has nanometer scale spinodal structure. With the increase of Y, the rod-like structure of spinodal structure became thin rod-like structure abviously. For example, the rod-like structure of (AlCrFeNiCo)97.5Y2.5 turn into spherical gradually, where the diameter only was 100nm . With the addition of Y, the hardness of alloy was improved, compressive strength and compression ratio were decreased, the cleavage fracture changing from to transgranular and cleavage fracture. With the addition of Y element in AlCrFeNiCoTi_0.5 alloy, the hardness of alloy was improved, the spinodal structure in center of grain became thin too . Netlike grain boundary was disconnected where Y-rich phase was found .The compressive strength and compression ratio of alloy were decreased, Fracture mechanism still is cleavage fracture.The TiC of AlCrFeNiCo-TiC composites have a morphology of regular polygon, they distribute equably .he grain of AlCrFeNiCo-TiC composites becaming thin obviously with the increasing of solidification rate, The grain of AlCrFeNiCo-5vol% TiC in high solidification rate was only 1/5 of the grain at low solidification rate. Solidification velocity has a great impact on TiC's shape but have a little influence on TiC's size. With the addition of Reinforcing phase in AlCrFeNiCo alloy, the compressive strength and compression ratio of alloy were increased. The hardness, compressive strength, compression ratio of AlCrFeNiCo-TiC composites were increased with the increasing of solidification rate. AlCrFeNiCo-5vol%TiC have a good comprehensive mechanical properties(547.1HV, 2369MPa, 29.15%) when it solidify at high solidification rate. During wear risistance testing, AlCrFeNiCoand AlCrFeNiCo-TiC composites perform the adhesive wear mechanism. There has a best addition of TiC, less than this addition, AlCrFeNiCo-TiC composites have a good mechanical properties .