Study On The Process And Mechanism Of The Zr-Based Bulk Metallic Glasses During Friction Stir Welding

To X-ray diffraction (XRD). differential scanning calorimetry (DSC), scanning electron microscopy (SEM) as the main means to target Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅ BMGs; the use of BMG in supercooled liquid region with The superplastic characteristics, based on the principles of friction stir welding, the use of orthogonal experiment method, the paper had BMG friction stir welding of the test.The BMGs is hard and has small plastic deformation in the temperature range between room temperature to glass transition temperature; while in the supercooled liquid region, the BMGs became softer, showed an excellent superplastic deformation ability, the stress was lower and the strain became higher. Designed to test the first four tools. Trials found that: the first small diameter of the friction weld using molding, large diameter shaft shoulder is more conducive to plastic flow of metal. The tool used had a shoulder 12 mm in diameter and a cylindrical pin 2 mm in diameter and 1.7 mm in length. The Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅ BMGs were successfully joined while the process parameters were as follows: the rotation rate of friction head was 600rpm, the welding speed was 30mm/min, and the plunge depth was 0.10mm. The Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅ BMGs and copper were successfully joined while the process parameters were as follows: the rotation rate of friction head was 600rpm, the welding speed was 40mm/min, and the plunge depth was 0.10mm.By orthogonal analysis of experimental data in the process of friction stir welding of the primary and secondary factors in the following order: Friction head diameter rotation rate→shoulder-axis diameter→plunge depth→welding speed. In the weld zone of the joint, the plastic flow patenr is obvious. During the friction stir processing, there is no other crystalline phase and the BMGs is still amorphous. No visible defects were observed in the metallograph of the polished cross-section of the welded BMGs, showing the achievement of metallurgical bonding of the BMGs. The X-ray diffraction patterns of the interface of the welded BMGs show that the existence phase is only glassy, and there is no crystallization was observed after welding. And no nano-crystalline due to plastic deformation was observed in SEM.