Study On Microstructure And Mechanical Behavior Of CoCrNi(Fe,Mn) Alloys

In this paper,austenitic CoCrNi(Fe,Mn)alloy was prepared by vacuum suspension melting and spark plasma sintering(SPS).The alloy was rolled at room temperature(298K)and low temperature(77K).The effects of rolling deformation on the microstructure and mechanical properties of the alloy were investigated.The effects of cold rolling and annealing on microstructure and mechanical properties of the alloy were studied.The effects of two preparation processes on the properties of the alloy were investigated.The grain sizes of the as-cast alloy are 110μm,225μm and 120μm,the tensile strength is 565 MPa,477MPa and 478 MPa,and the uniform elongation is 90%,71% and 49%,respectively.Rolled at room temperature,the tensile strength of 1645 MPa,1320MPa,1260 MPa,uniform elongation of 7%,6%,5%,respectively.Low temperature rolling,tensile strength of 1713 MPa,1342MPa,1341 MPa,uniform elongation of 7%,6%,7%,respectively.Rolling deformation significantly increases the strength of the alloy but loses plasticity.The wear resistance of CoCrNi medium entropy alloy is better,and the wear mechanism is oxidation wear,abrasive wear and adhesive wear.There are a lot of annealing twins in the alloy after cold rolling and annealing.The tensile strength of CoCrNi medium entropy alloy after cold rolling and annealing at 800°C is 888 MPa and the elongation is 41%.Compared with the rolling deformation process,the alloy has a good strength-plasticity matching.The grain sizes of the alloys sintered by SPS are 22μm,23μm and 29μm,and the densities are 95%,99% and 99%,respectively.Twin structures appear in the alloys,and the strength of the alloys increased by 32%,29% and 28%,respectively,compared with the ascast alloys.Co Cr Fe Ni high entropy alloy has good wear resistance,and the wear mechanism is oxidation wear,abrasive wear and adhesive wear.The alloy prepared by SPS has better wear resistance than the as-cast alloy.