The Research On Microstructure And Mechanical Properties Of Ti-based Amorphous Composites

Based on the theory of eutectic composition is easy to form amorphous and Inoue's three principles, this dissertation selected Ti-Ni-Cu eutectic composition (Ti_66.7Ni₂₀Cu_13.3) as the research object, on this basis, we carried out Zr replacement and Al,Si addition. Alloy samples of three groups were successfully prepared by copper mold casting method, that were Ti_66.7-XNi₂₀Cu_13.3Zr_X(X=0,10,30), (Ti_0.67Ni_0.2Cu_0.13)_100-XAl_X(X=0,1,3,5) and (Ti_0.66Ni_0.2Cu_0.13Al_0.01)_100-XSi_X (X=0,1,3,5), and eutectic composition samples have different diameters (Φ2mm,Φ3mm,Φ4mm andΦ6mm). The phase composition, microstructure, the surface of fracture and mechanical properties of the samples were examined by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and WDW-100J pressure testing machine, based on the results we researched the effects of diversification on microstructure and mechanical properties of the alloy samples.The results indicated that the alloys of Ti_66.7Ni₂₀Cu_13.3(Φ2mm,Φ3mm andΦ4mm), (Ti_0.67Ni_0.2Cu_0.13)_100-XAl_X(X=0,1,3) and (Ti_0.66Ni_0.2Cu_0.13Al_0.01)_100-XSi_X(X=0,1) were formed Ti-based amorphous composites by the method of copper mold casting, and this alloy samples have dense microstructure, good corrosion resistance, high ductility and high fracture strength. At the same time, the characteristic of the alloy samples'deformation during the compression was elastic-plastic deformation and the failure mode was the typical ductile fracture. The other alloy samples of Ti_66.7Ni₂₀Cu_13.3(Φ6mm), Ti_66.7-XNi₂₀Cu_13.3Zr_X(X=10, 30), (Ti_0.67Ni_0.2Cu_0.13)_100-XAl_X (X=5) and (Ti_0.66Ni_0.2Cu_0.13Al_0.01)_100-XSi_X (X=3,5) have most of the crystal phase, therefore, microstructures of the samples appear thick dendrites, the mechanical properties reduce all so, the characteristic of the alloy samples'deformation during the compression was elastic deformation, the failure mode was brittle fracture.Al, Si diversity (X=1) increased the fracture strength, especially when 1.at% of the Si content, the alloy sample has dense network organization, among the network organization is the small lamellar structure,and the snowflake-like organization presence in the structure, this structure has the highest fracture strength in all this tests, as1825Mpa, ductile deformation is 3.3%.Eutectic composition alloy sample has the highest ductile deformation, it's up to 4.8%, when diameter is 3mm.Φ4mm alloy has higher fracture strength, up to1756Mpa. That is, we can obtain Ti-Ni-Cu based amorphous composites with higher mechanical properties by copper mold casting method in a range of cooling rates.