Influence of particles on the functional properties of single crystals of high-strength ferromagnetic alloys

摘要

Single crystals of the ordered ferromagnetic Co_(49)Ni_(21)Ga_(30) (at.%) alloy with B2-L1_0 martensitic transformation and of the disordered iron-based Fe_(41)Ni_(28)Co_(17)Al_(11.5)X_(2.5) (X=Ta, Ti) (at.%) alloys, which undergo thermoelastic y-a' martensitic transformations, were studied in terms of the influence of chemical composition, size and volume fraction of the dispersed γ-phase particles on functional properties - shape memory effect and superelasticity. Single crystals of Co_(49)Ni_(21)Ga_(30) alloy showed that the precipitation of nanometric y'-phase particles changes the martensitic transformation characteristic temperature, reduces the value of the shape memory effect and superelasticity, increases thermal and stress hysteresis, and leads to hardening of the high temperature phase, which promotes superelasticity at a wide temperature range and at high temperatures at T>373K compared with the crystals without particles. Single crystals of FeNiCoAlX (X=Ta, Ti) alloys have experimentally demonstrated that the precipitation of ordered γ-phase particles at a size of d=5-10 nm during aging at T=973 K, 3 h, leads to the occurrence of the shape memory effect and superelasticity.