Martensitic transformation and magnetic transition of Co₄₁Ni₃₂Al_27-xSi_x alloy

The effects of Si on the martensitic transformation and magnetic transition of Co₄₁Ni₃₂Al_27-xSi_x alloys were investigated by optical micrography, DSC and VSM methods. The structure type of martensitic phase was determined by X-ray diffraction. Martensitic transformation temperatures of Co₄₁Ni₃₂Al₂₇ alloys are obviously elevated by the substitute of Si for Al element, the addition of 1% Si can increase the martensitic transformation temperature by about 50 K. Curie points are also increased with increasing of Si content, 1% Si can increase the Curie temperature by 10 K. Martensites are all of ordered L1₀ structure, but the unit cell volumes are decreased with increasing Si content. The reason for above results were discussed.