The Effect Of Alloying Elements Addition On The Glass Forming Ability And Corrosion Resistant Properties Of Cu-based Bulk Metallic Glasses

In this paper, Cu-based bulk metallic glasses were prepared by magnetic levitation melting - copper modle suction method. The structure, thermal behaviors and corrosion properties of bulk amorphous alloys were examined by XRD, DSC, SEM ,TEMand corrosion measuring system respectively. And the glass forming ability, thermal stability and corrosion resistant properties caused by the effect of addition of trace elements in Cu-Zr-Al system were investigated.Cone samples of Cu_50-xZr₄₂Al₈Gd_x (x=0,1,2,3,4,5) and Cu_50-xZr₄₂Al₈Nd_x (x=0,1,2,3,4) were prepared by magnetic levitation melting - copper modle suction method, and the glass forming ability and thermal stability were studied. The results showed that, the addition of trace rare earth elements Gd and Nd improved the glass forming ability and thermal stability in Cu-Zr-Al system. Cu₄₈Zr₄₂Al₈Gd₂,Cu₄₆Zr₄₂Al₈Gd₄,Cu₄₉Zr₄₂Al₈Nd,Cu₄₆Zr₄₂Al₈Nd₄ showed the better glass forming ability,and the critical size were 6-7mm,and the reduced glass transition temperatures T_rg separate were 0.614,0.650, 0.612, 0.605, and the parameterγwere 0.412,0.411,0.410,0.416,and the width of supercooled regionΔTx were69K, 32K, 61K, 73K. It was indicated that Cu₅₀Zr₄₂Al8, Cu₄₇Zr₄₂Al₈Gd₃, Cu₄₅Zr₄₂Al₈Gd₅,Cu₄₇Zr₄₂Al₈Nd₃ still had big GFA, the critical size were were 3⁵mm.The addition of Ag in Cu-Zr-Al system could improve the glass forming ability and thermal stability. The Cu_50-xZr₄₂Al₈Ag_x(x=2,3,4,5) fully bulk amorphous alloys were obtained by copper modle suction method, the diameter of which were 3mm. the glass forming ability improved as the Ag increased,and the width of supercooled regionΔTx,the reduced glass transition temperatures T_rg and parameter y were higher than Cu₅₀Zr₄₂Al₈ amorphous alloys, and critical cooling rate Rc were also reduced obviously. Then a large number of experiments were carried out, and Cu₄₅Zr₄₂Al₈Ag₅,Cu₄₃Zr₄₁Al₈Ag₈,Cu₄₀Zr₄₄Al₁₀Ag₆,Cu₄₃Zr₄₅Al₈Ag₄ fully bulk amorphous alloys were prepared by changing content, the diameter of which were 8mm,and the reduced glass transition temperatures T_rg were 0.625, 0.628, 0.618, 0.618, and the width of supercooled regionΔTx were 76K,84K,78K,77K,and the parameter y were 0.427,0.432,0.424,0.424.The corrosion behavior of Cu₅₀Zr₄₂Al₈,Cu₄₈Zr₄₂Al₈Gd₂,Cu₄₆Zr₄₂Al₈Gd₄, Cu₄₉Zr₄₂Al₈Nd₁ and Cu₄₆Zr₄₂Al₈Nd₄ in 3%NaCl aqueous solution were studied by immersion weight loss method and electrochemical method. The results of corrosion rate, micro-morphology and polarization curves showed that, corrosion resistant properties were reduced as the addtion of Gd and Nd. The open circuit voltage of amorphous alloys were negative and corrosion current density increased as the content of Gd and Nd increased. The corrosion resistant properties comparative study of Cu₄₅Zr₄₂Al₈Ag₅,Cu₄₃Zr₄₁Al₈Ag₈,Cu₄₀Zr₄₄Al₁₀Ag₆,Cu₄₃Zr₄₅Al₈Ag₄ amorphous alloys and crystalline alloy in 3%NaCl aqueous solution were carried out, and bulk amorphous alloys showed excellent corrosion resistant properties.