Structures and properties of bulk glass forming Ni Nb Sn alloys and Ni Nb Ta Sn alloys

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2007-03, Vol.449, p.134-138
• Main Authors: Choi-Yim, Haein, Xu, Donhua, Johnson, William L.
• Format: Article
• Language: English
• Subjects: Applied sciences; Elasticity. Plasticity; Exact sciences and technology; MATERIALS SCIENCE; Mechanical properties; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metallic glass; METALLIC GLASSES; Metals. Metallurgy; MORPHOLOGY; NICKEL ALLOYS; NIOBIUM ALLOYS; Other,OTHER; Phase separation; PHYSICAL PROPERTIES; TANTALUM ALLOYS; TIN ALLOYS
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2006.02.263

Ternary Ni 60Nb 40− x Sn x (3 ≤ x < 9 at.%) and quaternary Ni 60(Nb 100− x Ta x ) 34Sn 6 ( x = 20, 40, 60 and 80 at.%) Ni-base alloys were found to form bulk amorphous structures using conventional metallic-mold casting. These bulk amorphous alloys have very high glass transition temperatures (881 K < T g < 895 K). They also exhibit high Young's modulus (180–200 GPa), shear modulus (54–59 GPa), estimated strength (3–3.8 GPa) and measured compressive yield strength (2–2.8 GPa). The measured strength of the ternary alloys depends strongly on the Sn content and is generally lower than the strength estimated from modulus and hardness. Small-angle neutron scattering studies show that phase separation occurs in these alloys. The phase separation may be responsible for the strong composition dependence of the measured strength and the obvious discrepancy between the measured and the theoretical strengths (i.e. the premature fracture behavior).