Fabrication And Welding Of Zr-based Bulk Amorphous Alloy

Due to the high mechanical strength, the Zr-based bulk amorphous alloys with higher glass forming ability have promising application as structural materials. However, it is just the begaining on the study of the weldability of BMG.. This paper is mainly about the preparation and welding of Zr-based BMG.. Show in details as following aspects:Firstly, a Zr₅₅Al₁₀Ni₅Cu₃₀ bulk amoyphous column and plate were successfully fabricated by spray-casting system. the BMG structural reasearches have been investigated by X-Ray Diffraction(XRD), High Diffraction Transmission Electron Microscope(TEM) and Scanning Electronic Microscope(SEM), characteristic analyse by means of Differential Scanning Calorimeter(DSC) that indicates the T_x , T_g and ΔT_x of Zr₅₅Al₁₀Ni₅Cu₃₀ BMG 690K, 771K and 81K respectly.Secondly, Zr₅₅Al₁₀Ni₅Cu₃₀ BMGs have been welded to BMGs by liquid phase welding using spot welding and laser-beam welding methods with the crystallization occurrence. the joint after laser-beam welding loses 1/3 strength compared to the original tensile strength of Zr₅₅Al₁₀Ni₅Cu₃₀ BMG..Thirdly , Zr₅₅Al₁₀Ni₅Cu₃₀ BMG were successfully welded to the same while keeping the amorphous state by using the friction welding. Under the wide welding conditions of rotational speed (n) of 2500⁵000rpm, friction pressure (p1) of 80¹00MPa, t₁(friction time while the friction pressure of p1) of 0.1⁰.4s, p2(upsetting pressure) of 200MPa, t₂ (upsetting time) of 2s, successfully joints were abtained while no crystallization happening.Fourthly, fracture processes of metallic under compressive and tensile loading are significantly different. Compressve fracture surfaces only exhibit a vein-like structure with a rather uniform arrangement showing that thecompressive fracture should occure in a pure shear mode, while the tensile fracture surfaces have both the vein-like structures and core-like structures that indicate the tensile fracture shouldn't occure in pure shear mode. Both the compressive fracture angle (6>c = 43°) and the tensile fracture angle {6T = ST) are deviate from the maximum shear stress plane.