The Research On Superplastic Of Metallic Glass And Composite Materials In The Supercooled Liquid Region

In this paper, the glass forming ability(GFA) and mechanical with different content of Zirconium of [Zro.72+x(Cu0.59Ni0.41)0.28-x]88Al12(x=0,0.05,0.10) bulk amorphous alloy were studied, the major findings of the study are as follows:(1) The results show that the supercooled liquid region△Tx、the reduced glass transition temperature Trg and the parameter y decreases with the increase of Zr content, which results in the decrease of the thermal stability and GFA. The fracture strengths plastic strain and compressive strength reached the maximum value which are1531MPa、14.61%and1838MPa when x=0. However, the plastic strain and compressive strength when x=0.1are reached the minimum value5.06%and1495MPa. It is concluded that the quasistatic compressive mechanical properties decreased with the increase of Zr content.(2) The uniaxial compression test of bulk metallic glass was studied with different temperatures and strain rates in the supercooled liquid region. The results show that Zr-based bulk metallic glass has good superplasticity, and the ture stress decreases with the increase of strain rate, but the stress-strain curve has various tendency at different temperatures. The fracture surface morphology of the bulk metallic glass after compression in the supercooled liquid region showed as reverse N shape, the structure is amorphous-crystal composite. The strain rate sensitivity exponent m is about1when the strain rate is10-3to5×10-3s-1. The brittle parameters were calculated by VFT equation, which were22.81and18.30when the strain rate is10-2to5x10-4s-1. These suggest that the bulk metallic glass is strong liquid and has superplastic properties. According to extend exponential model to get the alloy constitutive equation, and successfully created the the processing map.(3) The uniaxial compression test of [Zro.72+x(Cuo.59Nio.41)0.28-x]88Al12(x=0.05,0.1) bulk metallic glass was studied in the room temperature and the supercooled liquid region. The result shows that: At the room temperature, the plasticity increased with the strain rate decreasing. Under the same compounds, the elasticity modulus increases with the increase of strain rate, while the plastic strain and compressive strength decreases. On the whole, the yield strength and fracture strength also decreased. When x=0.1and the strain rate is O.55×10-4s-1, the plastic strain、compressive strength and the breaking strength reached the maximum value which are6.77%、1758MPa and1629Mpa.(4) In the supercooled liquid region, when x=0.05, the samples hve superplastic property and the flow stress increased with the strain rate inceased, while the plasticity dropped. When x=0.1, all the samples were brittle fracture. The fracture surface morphology of the bulk metallic glass consists mainly of smoothing zone and the root patterms. When the deformation temperature reaches405℃and strain rate of5×10-3s-1, the fracture surface morphology of the bulk metallic glass after compression in the supercooled liquid region is no longer showed as reverse N shape, but as a round drum.