Injection Casting Method Research Articles

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

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; Ni61Nb35.5−x Zr3.5Sn 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 Ni2SnZr 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 Ni61Nb30.5Zr3.5Sn5 alloy. Compression tests reveal that the Ni61Nb33.5Zr3.5Sn2 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.

Plasticity enhancement of Mg 58Cu 28.5Gd 11Ag 2.5 based bulk metallic glass composites dispersion strengthened by Ti particles

We have successfully synthesized the Ti particles reinforced Mg 58Cu 28.5Gd 11Ag 2.5 metallic glass composites (BMGCs) rods with a diameter of 2–4 mm by injection casting method in an Ar atmosphere. The glass forming ability (GFA) and the mechanical properties of these Mg-based BMGCs have been systematically investigated as a function of volume fraction ( V f) of Ti particles. The results show that the compressive plasticity increases with the volume fraction of Ti particles. A drastic improvement of compressive plastic strain (reach up to 24%) occurs at the Mg-based BMGC with 40 vol.% Ti particles. In parallel, multiple shear bands were revealed on the sample surface after compression test. This suggests that these dispersed Ti particles can highly absorb the energy of shear banding and branch the primary shear band into multiple shear bands, thus decrease the stress concentration for further propagation of shear band and so as to significantly enhance plasticity. Additionally, the yield strength can be kept at 800 MPa as increasing the addition of Ti particles to 40 vol.%. This was found presumably due to the good bonding of interface between the Ti particle and amorphous matrix.

Effect of Nb on glass forming ability and plasticity of (Ti–Cu)-based bulk metallic glasses

A Ti 33Cu 47Zr 9Ni 6Sn 2Si 1Nb 2 bulk metallic glass has been developed by Nb partial substitution for Zr in Ti 33Cu 47Zr 11Ni 6Sn 2Si 1 alloy. The glass forming ability Ti 33Cu 47Zr 9Ni 6Sn 2Si 1Nb 2 alloy has been investigated using differential scanning calorimetry and X-ray diffractometry. Partial Nb substitutes for Zr promote the glass forming ability. Ti 33Cu 47Zr 9Ni 6Sn 2Si 1Nb 2 BMG with diameter of 3 mm can be fabricated by Cu-mold injection casting method. The glass forming ability of Ti 33Cu 47Zr 9Ni 6Sn 2Si 1Nb 2 alloy is enhanced by stabilizing the undercooled liquid against crystallization. The plastic strain up to 2.5% was obtained for Ti 33Cu 47Zr 9Ni 6Sn 2Si 1Nb 2 BMG compared to 0.15% for Ti 33Cu 47Zr 11Ni 6Sn 2Si 1 BMG, which demonstrates that small amount of Nb addition can have a dramatic effect on plasticity enhancement in Ti–Cu-based BMG. The intersection and branching of the shear bands are observed. The plastic strain of the Ti 33Cu 47Zr 9Ni 6Sn 2Si 1Nb 2 BMG can be improved by the generation of nanocrystalline particles, which lead to multiple shear bands.

Structural and mechanical characterizations of ductile Fe particles-reinforced Mg-based bulk metallic glass composites

In this study, the atomic composition of Mg 58Cu 28.5Gd 11Ag 2.5 which possess high glass forming ability (GFA) was selected as the matrix alloy for synthesizing the ductile Fe particles-reinforced Mg-based bulk metallic glass composites (BMGCs) by using injection casting method. The results show that the compressive ductility increases with the volume fraction of Fe particles and reaches up to the compressive plastic strain of 8% for the Mg-based BMGC with 20 vol.% Fe. In parallel, multiple-shear bands were revealed on the sample surface which is near the fracture area. This suggests that these Fe particles can branch primary shear band into multiple-shear bands and decrease the stress concentration for further propagation of shear band, and so as to enhance plasticity. Additionally, a slightly decreasing in yield strength with increasing the addition of Fe particles was found presumably due to the formation of brittle Fe 2Gd intermetallic phase at the interface between the Fe particle and amorphous matrix. In overall, the ductile Fe dispersoids would provide a good toughening effect in promoting the practical use of amorphous materials.

Effect of Nb and Y Additions on Glass Formation and Magnetic Properties in the Fe78B14Si8 Alloy

In the present work, the effect of small additions of Nb and Y to Fe78B14Si8 alloy is analyzed concerning its glass forming ability and magnetic properties. Small ingots were obtained by injection casting method into a cylindrical Cu-mold. Different casting machines were used in order to evaluate the role of processing parameters on glass formation. Hysteresis loops have been measured using a vibrating sample magnetometer (VSM) and inductive methods. Structural properties were measured using differential scanning calorimetry and X-ray diffraction (XRD). The glassy phase is obtained only with a small addition of both Nb and Y (4 and 3 at. %, respectively). Moreover, a complete glassy phase with good soft magnetic properties is obtained only with the use of water cooled Cu-mold. In such case, the saturation magnetization is 0.91 T with a coercive field of 170 A/m.

Mg-rich Mg–Ni–Gd ternary bulk metallic glasses with high compressive specific strength and ductility

In the present study, we show by tailoring the combinations of the bonding energy among the elements in the liquid state, glass forming ability and compressive mechanical properties of the metallic glasses (MGs) can be improved. The mixing enthalpy values for binary atom pairs in the ternary Mg–Ni–Gd alloys (Mg–Ni: −12 kJ/mol, Mg–Gd: −27 kJ/mol, Ni–Gd: −161 kJ/mol) covers a wide range, although they are all negative. Mg-rich Mg–Ni–Gd (Mg > 70 at.%) alloys can be readily solidified into an amorphous state in a wide composition range up to 4 mm in diameter using the injection casting method; they exhibit the highest level of glass transition temperature Tg among those reported in Mg-based MGs so far. In particular, Mg-rich Mg–Ni–Gd bulk metallic glasses with 10–15 at.% Ni and 10–15 at.% Gd exhibit high strength over 900 MPa and large plastic strain up to ∼2% during compressive loading.

Effect of Zr addition on the glass-forming ability and mechanical properties of Ni–Nb alloy

The effect of zirconium (Zr) addition on the glass-forming ability (GFA) and mechanical properties of the Ni61.5Nb38.5 alloy has been studied. The addition of Zr improves the GFA. When x = 5 for Ni61.5Nb38.5−xZrx (in at.%) alloys, the alloy exhibits the best GFA and can be cast into 3-mm-diameter amorphous samples by using the copper mold injection-casting method. Differential scanning calorimetry measurements indicated that the thermal parameters, such as Trg and γ, have not a good correlation with the GFA in the Ni–Nb–Zr alloys. Compression tests reveal that the addition of Zr just decreases the fracture strength slightly from 3.4 to 3 GPa and that all of the tested samples exhibit a little compressive plasticity of about 2%. When x = 9, the feature of the fracture surface indicates that the alloy has a tendency for transition from the ductile to the brittle. And delicate “dimple” and microscale vein pattern structures have been observed on it.

Enhancement of glass forming ability and plasticity by addition of Nb in Cu–Ti–Zr–Ni–Si bulk metallic glasses

The effect of Nb substitution for Zr on the glass forming ability (GFA) and mechanical properties of Cu 47Ti 33Zr 11− x Nb x Ni 8Si 1 ( x = 0, 2, 4, 6, 8, 11) alloys have been investigated using differential scanning calorimetry (DSC), X-ray diffractometry (XRD), high resolution transmission electron microscope (HRTEM), and atom probe field ion microscope (APFIM). Partial substitution of Zr by Nb in Cu 47Ti 33Zr 11Ni 8Si 1 promotes the GFA. Cu 47Ti 33Zr 11− x Nb x Ni 8Si 1 ( x = 2, 4) bulk metallic glasses (BMGs) with diameter of 5 mm can be fabricated by Cu-mold injection casting method. The plastic elongation of ∼4.2% in Cu 47Ti 33Zr 7Nb 4Ni 8Si 1 BMG, when compared with ∼1.5% in Cu 47Ti 33Zr 11Ni 8Si 1 BMG, demonstrates that small amount of Nb addition can have a dramatic effect on plasticity enhancement in Cu–Ti–Zr–Ni–Si BMG. HRTEM and APFIM results show that the as-cast Cu 47Ti 33Zr 7Nb 4Ni 8Si 1 BMG exhibits a fully amorphous structure without nm-scale compositional fluctuation, indicating that the plasticity of the BMGs can be improved even though no microstructural obstacles hindering or branching the propagation of the shear bands are observed by HRTEM and APFIM.

Amorphous phase formation in a Ni−Zr−Al−Y alloy system

Quaternary Ni-based amorphous alloys containing only metallic elements were developed through systematic alloy design. The importance of the phase equilibria information for the development of amorphous alloys was demonstrated through experimental results. Ni−Zr−Al ternary alloys having low liquidus temperature tend to have high GFA. Partial replacements of Zr with Y in the ternary alloys significantly enhanced the GFA of the quaternary alloys. The alloy Ni60Zr25Al8Y7 could be cast into a fully amorphous rod through an injection casting method. Since most Ni-based amorphous alloys reported to date contain non-metallic elements, the Ni-based amorphous alloys developed in the alloy system Ni−Zr−Al−Y are of interest.

Ti-Based Bulk Metallic Glasses with High Specific Strength

The glass forming ability of melt-spun Ti65-xZrxBe18Cu9Ni8 (x = 0, 5, 10, 15) amorphous alloys have been investigated by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). With increasing Zr contents, x from 0 to 15, ΔTx (= Tx − Tg), Trg (= Tg/Tl) and γ (= Tx/(Tg + Tl)), where Tg = glass transition temperature, Tx = crystallization temperature and Tl = liquidus temperature, gradually increase from 35 to 40 K, from 0.558 to 0.621, and from 0.378 to 0.406, respectively. The Ti65-xZrxBe18Cu9Ni8 (x = 10, 15) BMG cylinders with the diameter up to 6 mm are successfully fabricated by the injection casting method, exhibiting high Vickers hardness (681-700) and yield strength (2.0-2.1 GPa). Ti-Zr-Be-Cu-Ni alloys with >50 at% Ti content have higher specific strength than any other Ti-based BMGs reported so far.

Ni-Based Refractory Bulk Amorphous Alloys with High Thermal Stability

Enhancement of thermal stability and glass forming ability in Ni 60 Nb 40-x Ta x (x = 0, 3, 5, 10, 20 at%) alloys has been investigated. The crystallization temperature increases from 660°C in binary Ni 60 Nb 40 amorphous phase to 721°C in Ni 60 Nb 20 Ta 20 amorphous phase. The fully amorphous rod with diameter of 2 mm is fabricated in Ni 60 Nb 30 Ta 10 alloy by an injection casting method. The compressive failure strength of the Ni 60 Nb 30 Ta 10 bulk amorphous alloy is 3346 MPa.

CRYSTALLIZATION BEHAVIOR OF A BULK AMORPHOUS Zr64Cu18Ni10Al8 ALLOY

The bulk amorphous Zr 64 Cu 18 Ni 10 Al 8 alloy with a diameter of 5 mm was successfully obtained by an injection-casting method. The equilibrium crystallization temperature and the associated activation energy of the amorphous alloy were determined using differential scanning calorimetry and Kissinger's peak shift method. The mechanical properties were determined by microhardness. The results show that the bulk amorphous Zr 64 Cu 18 Ni 10 Al 8 alloy, the glass transition temperature is 380°C, the crystallization temperature is 482°C, the crystallization temperature at infinitesimal heating rate is extrapolated to be 442°C, the associated activation energy is 103 kJ/mol, and the Vickers hardness is 540 for the Zr 64 Cu 18 Ni 10 Al 8 bulk amorphous alloy. The energy barrier of crystallization for the amorphous Zr-based alloy is much less than the amorphous Fe- and Ti- based alloy. The hardness value of is 1.6 times larger than the cast titanium and steel. Therefore hopefully we can develop these bulk amorphous alloy into the application on sporting goods, micro-mechanical devices and aerospace industries.

Ni-based bulk amorphous alloys in the Ni–Ti–Zr–Si system

We report on the fabrication and properties of the new Ni-based bulk amorphous alloys in the Ni–Ti–Zr–Si system that have high glass forming ability (GFA) and large undercooled region ( ΔT X), which corresponds to the temperature difference between glass transition temperature and the onset temperature of a first crystallization event. The compositional range for the formation of the amorphous alloys that have large ΔT X (>30 K) is defined in the pseudo-ternary phase diagram Ni–(Ti,Zr)–Si. Some alloys can be fabricated as fully amorphous rods 2 mm diameter through an injection casting method. Si effects on the crystallization behavior of these new Ni-based amorphous alloys are also investigated and related to the GFA and the ΔT X.