Research On Mechanical Behavior Of Zr-Based Bulk Amorphous Alloy

Zr-based bulk amorphous alloys, especially Zr-Ti-Cu-Ni-Be amorphous alloy system have very good prospect because of its high strength, high hardness, high wear resistance, good corrosion resistance and cause the attention of many researchers. Zr_41.2Ti_13.8Cu_12.5 Ni₁₀Be_22.5(Vit1) and Zr_46.8Ti_8.2Cu_7.5Ni₁₀Be_27.5(Vit4) two large amorphous alloys are typical representative of the Zr-based amorphous alloy. This paper research on the routine mechanical properties of the two large amorphous alloys and using cycle pre-load approach to improve the mechanical properties and the tensile plastic, compression plastic of bulk amorphous alloys.Compressive mechanical properties and tensile mechanical properties at room temperature of Vit1 and Vit4 bulk amorphous alloys were studied, the results showed that: The compressive strength of Vit1 was between 1880MPa-2050MPa, the compressive strength of Vit4 was about 1900MPa, two large amorphous alloy total elongation was break at 6%-9%, and plastic strain was at 0.3%-2%, and compressive fracture mode was shear fracture. Tensile mechanical properties at room temperature results show that: Vit1 tensile strength was between 1700MPa -1900MPa, Vit4 had the lower tensile strength only 1600MPa. The total elongation breaks of the two bulk amorphous alloys were at 2%-3.5%, most deformation was the elastic deformation, almost no plastic deformation. There had variety of fracture mode, shear fracture, and level fracture, and there were much fracture generally 2-3 fracture.Cycle pre-load of Vit1 and Vit4 two bulk amorphous alloys and compressive properties after simple tensile rupture and cycle pre-load tensile fracture of Vit1 and Vit4 two bulk amorphous alloys were tested, cycle pre-load test same with the tensile test, Vit1 was set pre-cycle 20 circles, 300 circles, 1000 circles, the experiments show that more than 300 circles, the mechanical properties of the bulk amorphous alloys has not been increased, the phenomenon of cyclic softening did not happen, and no plastic deformation, Instead, the mechanical properties of 20 cycles improve slightly, had higher tensile strength, and the plastic deformation rate was increased. Therefore, Vit4 was set 60 cycles when it carried out the cycle pre-load, the result show that the tensile strength significantly increased when Vit4 through 60 circles, the plastic deformation rate reached 0.34%. The amorphous alloy samples were compression tested after simple tensile fracture and cycle tensile fracture, the measurement results show that the compressive strength of most of them more than 2000MPa, the total fracture deformation was between 7%-8%, and plastic deformation rate between 1%-3%, the largest plastic strain is 2.57%. From the experimental results can be seen the compressive strength, fracture total elongation rate and the total rate of plastic deformation all increases when compression alone, the compression after tensile fracture and compression after cycle-load fracture of the two amorphous alloys. It explains that the tensile and cycle load had greater impact on total elongation rate and plastic deformation rate of the bulk amorphous alloys. Description so that cyclic loading on the mechanical properties of amorphous alloys has improved significantly.