Microstructure And Mechanism Of In-situ Synthesis Of Reinforcing Phase In TiC/AlCrFeNi-M High-entropy Alloy Based Composites

The design of multi-component high-entropy alloys has brken traditional metalmaterial design patterns. By rational elements design, high-entropy alloys with excellentperformance of high hardness, high temperature resistance, corrosion resistance wasobtained. To further enhance the performance, high-entropy alloy matrix compositeswere developed. It combines high modulus and hardness of reinforcing phase with hightemperature resistance and other properties of high-entropy alloys, which has greatscientific values and broad application prospects.This research prepared in situ TiC/AlCrFeNi-M high-entropy alloy matrixcomposites with vacuum arc melting furnace. Microstructure and formation mechanismof TiC phase, interactions between dislocations and nano precipitated and affects ofhigh energy ball milling to the composites were studied with different testing methods,such as differential thermal analysis(DSC), scanning electron microscopy (SEM),transmission electron microscopy (TEM), energy spectrum analysis(EDS) and ect.It is found that, TiC/AlCrFeNi-M high-entropy alloy matrix composites have thesame simple crystal structure with its matrix. Compared with the matrix, compositeshave lower melting point.There are two kinds of formation mechanism of in-situsynthesized TiC reinforcement in TiC/AlCrFeNi composites, one is the transformationof ternary compound and the other is the solution and precipitation of [Ti] and [C]atomic. Those chunk polygonal TiC and crosswise TiC phase were transformed fromternary compounds while ubmicron TiC phase were formed through solution andprecipitation. In-situ synthesis modes of TiC phase were put forward. The dispersivelydistributed TiC phase, which is obtained by the direct response of [Ti] and [C] atom,was the ideal reinforcement. The TiC phase was fine in size, single in shape anddispersive in distribution in those composites prepared with milled graphite powder.What is more, the reinforcement was in nano size in TiC/AlCrFeNi high entropy alloymatrix composites with2.5%Vol reinforcement.In thermal mismatch area of TiC phase, nano hardness if the matrix and nucleationrate of nano precipitated were increased with the decreased distance to reinforcing phaseinterface. Formula of nucleation rate of nano precipitated in thermal mismatch area wasput foward.