Fabrication Of Cu-based Bulk Metallic Glasses Of Micro-alloying And Research On It's Mechanical Property

In this paper, a series of Cu_50-xZr₄₂Al₈M_x (M=Gd, Nd, Ag) bulk amorphous alloys were prepared by magnetic levitation melting-copper modle suction method. And the glass forming ability, thermal stability and mechanical properties of bulk amorphous alloys were examined by XRD, TEM, DSC, mechanical property tester, SEM and electron probe analyzer respectively. The main results are as follows:Firstly, the glass forming ability and thermal stability of Cu_50-xZr₄₂Al₈Gd_x(x=0,2,4) Cu_50-xZr₄₂Al₈Nd_x(x:=0,l,3,5) and Cu_50-xZr₄₂Al₈Ag_x(x=0,2,3,4)bulk amorphous alloy rod were studied. The results showed that, in the Cu_50-xZr₄₂Al₈Re_x(Re=Gd,Ag) BMG alloys,â–³T_x was in between 59 and 71, T_rg was in the range of 0.60-0.63, which indicated that the glass forming ability and thermal stability of samples were inproved.â–³T_x was in between 69 and 92 and T_rh was in the range of 0.60-0.62 as adding Gd with 2at.%-4at.%. The thermal stability of Cu₄₆Zr₄₂Al₈Re₄ was markly inproved.Secondly, the vickers hardness of Cu_50-xZr₄₂Al₈M_x(M=Gd, Nd, Ag) with 3mm in diameter was examined by brinell and vickers optical hardness tester. And the addition of rare earth elements Gd and Nd decreased hardness of bulk amorphous alloy. While adding Ag, vickers hardness improved as Ag increased. The vickers hardness of Cu₅₀Zr₄₂Al₈ (x=0)was 406, and that of Cu₄₆Zr₄₂Al₈Ag₄(x=4) was up to 527.Thirdly, tensile property of as cast dumbbell shaped Cu₅₀Zr₄₂Al₈ bulk amorphous alloy was tested, and compared with tensile property after isothermal annealing.The fracture mechanism in the two condition was discussed. The results showed that, after heat treatment, tensile strength and plasticity of the sample were improved, fracture strength and maximum strain value were 755MPa and 0.80%, respectively. Tensile property of Cu₅₀Zr₄₂Al₈ amorphous thin ribbons which were prepared by single-roll strip cast was also studied. And only elastic deformation occurred in tensile process, and the tensile strength was 549.7MPa.Finally, compressive property and fracture morphology of Cu₅₀Zr₄₂Al₈M_x (M=Gd, Nd, Ag) amorphous bar were examined. The results showed that, compressive strength of Cu₅₀Zr₄₂Al₈M_x(M=Gd, Nd) was decreased as adding Gd, Nd. The addition of Ag increased compressive strength of bulk amorphous alloy, and all of the fracture forms were typical brittleness fracture, fracture surface showed vein-like pattern. The maximum compressive strength and strain value of Cu₄₆Zr₄₂Al₈Ag₄ were up to 2038MPa and 4.25%, respectively. The bending properties of Cu₄₇Zr₄₂Al₈Ag₃ and Cu₅₀Zr₄₂Al₈ were studied . The bending strength of Cu₄₇Zr₄₂Al₈Ag₃ was up to 2955MPa in contrast with 2717.57 Mpa of Cu₅₀Zr₄₂Al₈ bulk amorphous alloys.