材料期刊网

The effect of tin (Sn) addition on the glass forming ability (GFA) and mechanical properties of the Ni-Nb-Zr ternary alloy system has been studied. The addition of Sn improves the GFA; Ni(61)Nb(35.5-x) Zr(3.5)Sn (x) (in at.%) alloys with x=1 can be cast into amorphous samples at least 3 mm in diameter using a copper mold injection-casting method. The critical size for glass formation decreases to 2 mm when x=5 because Ni(2)SnZr phase precipitates readily. The addition of Sn is also effective in enhancing the stability of the supercooled liquid; a maximum supercooled liquid region of 48 K was attained for the Ni(61)Nb(30.5)Zr(3.5)Sn(5) alloy. Compression tests reveal that the Ni(61)Nb(33.5)Zr(3.5)Sn(2) alloy possesses the best mechanical properties, with yield strength similar to 3180 MPa, fracture strength similar to 3390 MPa and plastic strain similar to 1.3%. The fracture surfaces examined by scanning electron microscopy indicate that the alloys have a transition from ductility to brittleness in fracture behavior. The combination of high GFA, high thermal stability, high strength and compressive plasticity makes these alloys potentially attractive for engineering applications.