Preparation And Study On Properties Of Ni-based Bulk Amorphous Alloys

In this paper, Ni_77-x-yMo_xCr_yNb₃P₁₄B₆（x=7 y=0、x=8 y=0、x=9 y=0、x=5 y=3、x=5 y=5、x=5 y=8、x=8 y=3、x=8 y=5, all in at.%） and Ni_76-xFe_xP₁₄B₆Ta₄（x=10、20、30、40%） bulk metallic glasses（BMGs） were successfully prepared by the Flux and J-quenching technology, and the glass forming ability, thermal stability, corrosion resistance and mechanical properties of the system were studied. The main work involves the following two parts.（1） We systematically study the effects of the content of Mo and Cr on the GFA,thermal stability, mechanical and corrosion resistance properties of Ni77-x-yMox CryNb3P14B6. In this experiment, we have successfully prepared Ni_77-x-yMoxCryNb₃P₁₄B₆（x=7 y=0、x=8 y=0、x=9 y=0、x=5 y=3、x=5 y=5、x=5 y=8、x=8 y=3、x=8 y=5, all in at.%） BMGs, When x=5 y=5, the maximum critical size for bulk amorphous alloy rod prepared can reach 1.5 mm. It is found that the partial substitution of Mo, Cr for Ni can enhance the glass forming ability（GFA） of the present Ni-based alloys, while excessive substitution will lead to the degradation of the GFA. The research results show that the corrosion resistance of the present Ni-based BMGs exhibit excellent corrosion resistance, and the magnitude of their corrosion current density can reach 10-6A/cm2, while their corrosion current density of the vast number of BMGs is greater than the magnitude of 10-5A/cm2. Furthermore,Ni-based bulk amorphous alloys also exhibit good mechanical properties, and the fracture strength is above 2400 MPa. Studies have shown that the plastic deformation of bulk amorphous alloys is mainly related to the Poisson’s ratio and Young’s modulus.The smaller the Poisson’s ratio, the smaller the young’s modulus, the larger the plasticity of the corresponding bulk amorphous alloys. Compared to Ni, Fe has a smaller Poisson’s ratio and a higher Young’s modulus, So according to the currentlyaccepted theories. at present we have prepared Ni based bulk amorphous alloy plastic compared to the Fe based bulk amorphous alloy should have more plasticity, but the Fe based bulk amorphous alloy has good plasticity. the plasticity of Ni based bulk amorphous alloys is almost zero compared with that of Fe based alloys. For a deeper understanding of this reason, it is also needed to seek answers to the analysis of the microstructure in a deeper level.（2） In this experiment, we have successfully prepared a new series of Ni_76-xFe_xP₁₄B₆Ta₄（x=10、20、30、40%, all in at.%） BMGs, and the critical diameter of this Ni-based BMGs reach the maximum value of 3.0 mm. The influence of the substitution content of Fe for Ni on GFA, thermal stability, corrosion resistance and mechanical properties of this Ni-based BMG are systemically studied. The results showed that the partial substitution of Fe for Ni can enhance the GFA of the present Ni-based alloys, while excessive substitution will lead to the degradation of the GFA.The corrosion resistance test shows that the corrosion current density of the present Ni-based BMGs 1M HCl and 1M NaCl solutions is in the order of magnitude10-5A/cm2, exhibiting good corrosion resistance, which is far less than that of the other BMGs even containing Mo and Cr. The compressive test show that the present Ni-based BMGs possess a high fracture strength（over 2500 MPa） as well as a large room temperature plasticity. Especially, the present Ni-based BMGs with x=20 exhibt a room temperature plasticity of 6.6%, which is the largest one reported to date for Ni-based BMGs.