Effect of Sn addition on the glass-forming ability and mechanical properties of Ni-Nb-Zr bulk metallic glasses

Abstract

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 ~3180 MPa, fracture strength ~3390 MPa and plastic strain ~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. Bulk metallic glasses (BMGs) have attracted much attention from scientists and engineers over the past few decades, since they possess such promising properties as high yield strength, hardness and elastic strain limit, along with relatively high fracture toughness, fatigue resistance and corrosion resistance [1][2][3]. In the case of Ni-based alloys, glassy rods up to several millimeters in diameter have been successfully fabricated from many alloy systems, such as, etc. These Ni-based bulk metallic glassy alloys have been reported to exhibit high strength (ranging up to 3000 MPa), high thermal stability (glass transition temperature generally around 880 K) [9,10], and excellent corrosion resistance [11]. The combination of superior properties enables them to have promising applications as engineering materials, such as for pressure sensors and micro-geared motors [12]. However, the achievement of a higher GFA for Ni-based amorphous alloys is still a challenging subject. So far the maximum dimension of Ni-based metallic glassy samples without noble elements is only 5 mm, which is much lower than that for other alloy systems, such as Zr-, Mg-, Ti-, Cu-, or Fe-based BMGs. Furthermore, most of the Ni-based BMGs exhibit a narrow supercooled liquid region (less than 40 K), which is not sufficient for processing. Thus, the development of new Ni-based BMGs with higher GFA as well as wide supercooled liquid region is of great importance. It was reported that BMG samples up to 3 mm were fabricated in the Ni-Nb-Sn [8] and Ni-Nb-Zr [13] alloy systems. The composition regions for glass formation in these simple ternary systems are located in the range of Ni 60 Nb 40-x Sn x (3<x<9) and Ni 61.5 Nb 38.5-x Zr x (0<x<9), respectively. The atomic radii of Sn (0.162 nm) and Zr (0.160 nm) are nearly equivalent. The mixing enthalpies between the constituent elements are negative: 30, 49, ...

Y and Er minor addition effect on glass forming ability of a Ni–Nb–Zr alloy

“…For the Y doped alloy, the mixing enthalpies of Ni-Nb, Ni-Zr, Ni-Y, Nb-Zr, Nb-Y and Zr-Y pairs are À30, À49, À31, 4, 30 and 9 kJ/mol, respectively [23]. This shows that the bonding between Ni-Zr, Ni-Y and Ni-Nb pairs is stronger than that between Nb-Zr, Zr-Y and Nb-Y implying that stronger pairs have a larger tendency to cluster, which would make inter-atomic diffusion difficult [24]. For the Er doped alloy, the mixing enthalpies of Ni-Nb, Ni-Zr, Ni-Er, NbZr, Nb-Er and Zr-Er pairs are À30, À49, À33, 4, 25 and 7 kJ/mol, respectively [23].…”

Impact of sulfur addition on the structure and dynamics of Ni–Nb alloy melts

“…Therefore, the binary alloy system has been often fine-tuned using minor-or micro-alloying, conventionally by adding metallic elements, such as Sn, Zr, and Ta. [7][8][9] In contrast to these metallic elements, just recently, using metalloid elements, such as P and S, as alloying components has been shown to be highly beneficial for glass formation and thermal stability. While P has also been used as an alloying element for Pd-or Fe-based BMGs, particularly sulfur as an alloying element has not been widely used before for BMGs, despite its wide availability in various industrial processes.…”

Effect of Annealing on the Curie Temperature in the Bulk Amorphous Alloys

“…At this point, polycrystalline materials often do not have satisfactory properties In this field. The answer to the search for materials that meet the high demands on the magnetic properties of alloys are rapid cooled materials [1,[5][6][7][8][9][10]. Despite the identical chemical composition, these materials have completely different properties than their crystalline counterparts.…”