Effect Of Aging Treatment On The Mechanical Properties And Corrosion Behavior Of FeMnAlNi

The polycrystalline alloy FeMnAlNi,as a new type of iron-based shape memory alloy,has good memory properties and exhibits excellent superelasticity in a wide temperature range,which has potential application prospects.However,the strength of the alloy based on the thermoelastic martensitic transformation of this system is low,so far there are few reports on the evaluation of indispensable corrosion.In this paper,a superelastic FeMnAlNi alloy was prepared by adding a small amount of C element.After smelting,solidification,homogenization,forging and rolling,a cold-rolled sheet with a thickness of 1 mm is obtained.Through OM,SEM,AFM,TEM,XRD,Raman spectrometer and other means,the organization observation and structure analysis at each stage were carried out.Through the tensile experiment,immersion experiment,electrochemical experiment,etc.,the effect of aging time(0-12 h)on the mechanical properties and corrosion properties of FeMnAlNi alloy was comparatively studied.The results show that FeMnAlNi alloy is mainly composed of high temperature austenite ? phase and low temperature martensite ? phase.After high temperature solution treatment and quenching treatment,? single-phase structure can be obtained.With the increase of the number of heat treatment cycles,(1250 ?,30 min ? 900 ?,45 min,it is a cycle heat treatment,and finally heat preservation at 1250 ? for 1 h,water cooling),the crystal grain grows abnormally,and the superelasticity increases.The samples aged 0-12 h at 200 ? were observed by TEM,and the existence of B2 phase coherent with the parent phase was found.When the aging time is prolonged,the B2 phase gradually grows,and the hardness of the alloy sample increases significantly(maximum HV: 530).Under 6% tensile deformation,the superelastic strain reaches its maximum(3.97 %)at 1h of aging,and the recoverable strain rate reaches its maximum(89.7 %)at 3 h of aging.The corrosion rate after aging treatment is lower than the corrosion rate without aging treatment,and the corrosion rate after aging at 200 ? for 3h is 0.08 mm/a.Electrochemical impedance spectroscopy shows that the impedance radius is the largest when aging at 200 ? for 3h.The polarization curve results show that the self-corrosion potential is the most positive when aging at 200 ? for 3h,which is-0.37V.The corrosion resistance of the sample is the best when aging at 200 ? for 3h.it is good.