Ions Implantation Of Cu-based Bulk Amorphous Alloys And Magnetoresistance Effect

In this paper, bulk amorphous alloys Cu₅₅Zr₄₀Al₅ and Cu₄₈Zr₄₅Al₇ were prepared successfully by means of copper-mold vacuum suction casting and implanted with Co and Mo ions by MEVVA source ions implanted machine.The thermal stability and mechanical properties of these alloys were investigated by differential scanning calorimeter(DSC), X-ray diffraction(XRD), four-probe method and X-ray photoelectron survey(XPS).The structure,Vickers-hardness(HV),ions distribution and magnetoresistance of the ions implanted bulk amorphous alloys were also studied. The results are summarized as follows:1. T_g,T_x,T_p andΔT_x values of Cu₄₈Zr₄₅Al₇ bulk amorphous alloy increase with the increase of heating rate.The bulk amorphous alloy has a significant kinetic effect. When the heating rate becomes smaller and smaller, T_x tends to constant value 492.5℃. The HV of Cu₅₅Zr₄₀Al₅ bulk amorphous alloy increases with the increase of anneal temperature. The wear resistant of the sample after annealing with high temperature is improved.2. After the bulk amorphous alloys are implanted with Co and Mo ions, their area of crystallization of DSC curves increase.Their T_x and T_p all move to the low temperature zone. XRD of their surface layer keeps diffuse diffraction (35°- 45°) of amorphous structure, but ZrO₂ phase of crystallization appears.Their HV becomes higher.3. In the surface layer of Cu₄₈Zr₄₅Al₇ bulk amorphous alloy which was implanted with Co ions, Co appears from the surface to depth of 200nm. From surface to depth of 20nm, Co amount increases.From depth of 20nm to105nm, it decreases. From depth of 105nm to 130nm, it increases again, and reach to the maximum mount at depth of 130nm. After that, it gradually lowers and disappears finally.4. The resistivity of the bulk amorphous alloys after ions implanting decreases.After Cu₄₈Zr₄₅Al₇ bulk amorphous alloys were implanted with Co ions,its magnetoresistance increases with the increase of external magnetic field at constant current.The magnetoresistance become prominently under low applied current. Under a steady external magnetic field, the magnetoresistance decreases slowly and tends to zero finally with the increase of the applied current.