Copper Mold Injection Casting Research Articles

Design Optimization and Mechanical Properties of SiC Particle Reinforced Ti-Based Metallic Glass Matrix Composite.

Ti-based bulk metallic glass (BMG) alloys have attracted widespread attention due to their strong glass forming ability, high specific strength, and good corrosion resistance. However, the poor plasticity of BMGs limits their further application in the aerospace and aircraft fields, as well as others. We optimized the composition of SiC-reinforced, Ti-based metallic glass matrix composites (MGMCs) through finite element modeling (FEM). FEM of MGMCs containing irregularly shaped SiC particles with different contents was conducted. Stress and strain analyses were conducted to evaluate the effect of the particle volume fraction on the mechanical behavior of MGMCs, and an optimization value of 30% was obtained, which is conducive to plasticity improvement. Arc melting copper mold injection casting was used to verify the optimized SiC content. The results show that the electroless nickel plating treatment effectively improves the wettability between SiC particles and the amorphous matrix, enabling the successful preparation of SiC/MGMC with a volume fraction of 29.5% through traditional injection casting. The volume fraction of SiC plays a crucial role in the transition of fracture mode from splitting to shear in MGMCs. After adding lightweight SiC particles, the yield strength, plasticity, modulus, and specific strength were improved by 25%, 1471%, 46%, and 33%, indicating that the use of nickel-plated SiC particles in MGMCs is an effective strengthening and toughening method for BMGs.

High-strength Cu–Ti-rich bulk metallic glasses and nano-composites

Abstract Cu47Ti34Zr11Ni8, Cu47Ti33Zr11Ni8Fe1 and Cu47Ti33Zr11Ni8Si1 bulk glassy alloys were prepared by injection copper mold casting. Mechanical properties, glass-forming ability, thermal stability and microstructural characteristics of as-cast rods were investigated. Calorimetric studies indicate a beneficial role of small Si or Fe addition on the thermal stability of Cu–Ti – Zr –Ni bulk glassy alloys. Compression tests reveal fracture strengths of 2040 to 2190 MPa, Young’s moduli of 100 to 109 GPa and elastic strains up to 2.4 %. The Si-containing glassy alloy exhibits a plastic elongation of 2.2%. The significant increase in plasticity observed for the Si-containing alloy is due to a special bimodal composite structure consisting of nano-scaled Cu crystals homogeneously dispersed in the bulk metallic glass matrix. The increase of the global plasticity can be explained by the formation of multiple shear bands that make the glassy alloy resistant to crack propagation.

Microstructural evolution and mechanical properties of rapidly solidified Ni-Ge alloys

Structural evolution and mechanical performances of rapidly solidified Ni95Ge5 and Ni33Ge67 alloys were investigated under two conditions involving drop-tube containerless processing and copper-mold injection casting. As the cooling rate increased, the coarse dendritic structure of the primary (Ni) phase for Ni95Ge5 alloy changed to equiaxed grains structure, and the microstructure of Ni33Ge67 alloy showed a transition from coarse (NiGe + Ge) eutectic to refined structure plus some primary Ge phase. Containerless processing can produce finer microstructures than those of injection casting owing to higher cooling rate. Nanoindentation measurements indicated that both alloys showed a remarkable enhancement of Vickers hardness along with the microstructural evolution, and the hardening mechanism for a single-phase alloy was found to be grain-boundary strengthening, while that of the eutectic alloy was attributed to the multiphase coordinated strengthening. The strain hardening exponents of Ni95Ge5 and Ni33Ge67 alloys were calculated as 0.28 and 0.77, respectively. The special morphology evolution and lower strain hardening exponent of Ni95Ge5 alloy remarkably improved the hardening ability. Its hardness increased up to 56.6% that was much higher than the eutectic alloy. Moreover, these alloys displayed different relations between hardness and strength. The average ratio of hardness to strength for Ni95Ge5 alloy was 2.75, while that for Ni33Ge67 alloy was 9.09. Both the experimental evidence and theoretical analysis revealed that obvious enhancements of hardness and strength were achieved using a high cooling rate; thus, the drop-tube processed alloy particles showed better mechanical properties than those of the as-cast alloys owing to their higher cooling rates. It is obvious that rapid solidification conditions can improve the mechanical properties of both the alloys to various degrees.

Enhancing strength and plasticity of Zr-based bulk metallic glasses by Zr partially substituted Fe and isothermal annealing

Zr-based bulk metallic glasses (BMG) Zr65+xCu17.5Fe10-xAl7.5 (x = 0, 2.5, 5, 7.5) with high zirconium content were prepared by an injection copper-mold casting method. The influence of Zr partially substituted Fe and isothermal annealing on the microstructure and mechanical properties of the Zr65+xCu17.5Fe10-xAl7.5 BMGs has been systematically studied. The as-prepared BMG with a Zr content of 70 at.% achieves superior glass forming ability with a large supercooled liquid region width of 82 K and compressive performance. An optimized isothermal annealing (0.5 h) below the glass transition temperature of the as-cast Zr70Cu17.5Fe5Al7.5 BMG contributes significant enhancement in compressive fracture strength and plasticity, from 1845 MPa and 7.4% (as-cast) to 2096 MPa and 12.7% (annealed), respectively. The result of the present study provides a new strategy for designing high-performance BMG-based alloys.

Significant room-temperature plasticity in a high Zr-containing bulk glassy alloy

Abstract

Effect of Ti addition on mechanical properties and corrosion resistance of Ni-free Zr-based bulk metallic glasses for potential biomedical applications

Toxic element free-Zr-based bulk metallic glasses (BMGs) have attracted considerable attentions for biomedical applications, in term of their excellent bio-corrosion and mechanical properties. In the present work, we fabricated a series of Zr65-xTixCu20Al10Fe5 (x = 0, 2, 4, 6 and 8) alloys using the injection copper-mold casting method, and reported the significant effect of Ti addition both on mechanical performance and corrosion behavior. It is found the glass forming ability (GFA) and plasticity are significantly improved by increasing Ti content up to 2 at.%, but deteriorated after excess Ti additions. The obtained Zr63Ti2Cu20Al10Fe5 amorphous alloy provides the largest supercooled liquid region width of 73 K, compressive fracture strength of 1905 MPa and plasticity of 8.57%, which are much higher than 67 K, 1854 MPa and 5.43% of the pristine Zr65Cu20Fe5Al10 BMG. However, the electrochemical measurements show that as-prepared Zr63Ti2Cu20Al10Fe5 alloy exhibits a terrible passivation ability and inferior corrosion resistance in phosphate-buffered saline (PBS) solution, which is mainly ascribed to the numerous defects in the passive films. On the contrary, further addition of Ti to 4–6 at.% promotes the intactness of passive film for Zr-based BMGs and enhances their resistance to pitting corrosion, in despite giving rise to unsatisfied mechanical performance.

Ti substituted Ni-free Zr65-xTixCu17.5Fe10Al7.5 bulk metallic glasses with significantly enhanced glass-forming ability and mechanical properties

We report the significant effect of Ti substitution on GFA and mechanical properties of Ni-free Zr-based BMGs. A series of Zr65-xTixCu17.5Fe10Al7.5 (x = 0, 2, 4, 6, 8) bulk alloys were fabricated by the injection copper-mold casting method, and new Zr65-xTixCu17.5Fe10Al7.5 BMGs with Ti content of 2–6 at.% were developed. Both the GFA and mechanical properties of the Zr65-xTixCu17.5Fe10Al7.5 alloys are significantly enhanced with the increase of Ti content up to 4 at.%. The as-prepared quinary Zr61Ti4Cu17.5Fe10Al7.5 BMG shows the largest supercooled liquid region width of 86 K, compressive fracture strength of 1915 MPa and compressive plasticity of 11.4%, which are much higher than 38 K, 1745 MPa and 3.0% of the pristine Zr65Cu17.5Fe10Al7.5 BMG.

Influence of laser surface melting treatment on the surface composition and mechanical properties of a Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glass

A Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glass (BMG) containing immiscible elements was prepared in the diameter range up to 5 mm by injection copper mold casting. The effects of the laser surface melting (LSM) treatment on the surface composition and mechanical properties of the Zr-based BMG were examined. It is found that the plasticity of the LSM-treated specimens is improved significantly by ~50% as compared with that of the as-cast ones, accompanied by the enrichment of Zr content through the reductions in Cu and Ag elements by LSM-induced evaporation. It is further noticed that the enhancement of plastic deformability is much distinct for the specimen with a larger size. The effects of LSM treatment is studied by considering the LSM-treated specimen as a kind of composite with the uninfluenced zone as the substrate and the influenced zone as the second phase. The plasticity enhancement of LSM treatment is closely related to the interaction between the influenced zone and the uninfluenced zone. Furthermore, it is assumed that the effectiveness of LSM treatment in plasticity enhancement will decrease when the volume fraction of the influenced zone exceeds a critical value due to the lack of interaction between the influenced zone and the uninfluenced zone, which is consistent with the experimental results. These results are promising for extending the applications of LSM treatment for the improvement of mechanical properties of BMGs.

Co substituted Zr-Cu-Al-Ni metallic glasses with enhanced glass-forming ability and high plasticity

Zr-based bulk metallic glasses have been considered as promising engineering materials. However, their widespread application is limited by their contrasting properties of glass-forming ability (GFA) and plasticity. Herein, the effects of Ni substitution by Co on the GFA and plasticity of the representative Zr-based metallic glass of Zr65Cu17.5Al7.5Ni10 were investigated. A series of Zr65Cu17.5Al7.5Ni10−xCox (x=0, 2, 4, 6, 7, 8, 10) rod samples with 2mm in diameter were prepared by injection copper mold casting method. Amorphous structure was successfully achieved when the Co content is less than 8at.%. Importantly, the Co addition contributed to significant enhancements in both GFA and plasticity of the amorphous Zr65Cu17.5Al7.5Ni10−xCox (x=0, 2, 4, 6, 7) alloys. The as-prepared Zr65Cu17.5Al7.5Ni8Co2 amorphous alloy shows the best and attractive performance with a supercooled liquid region width of 80K and a compressive plasticity of 7.4%, which are much higher than 50K and 0.2% of the pristine Zr65Cu17.5Al7.5Ni10 amorphous alloy, demonstrating that the Co substituted Zr-Al-Ni-Cu metallic glass has the potential to be used for engineering applications.

High formability of glass plus fcc-Al phases in rapidly solidified Al-based multicomponent alloy

A multicomponent Al84Y9Ni4Co1.5Fe0.5Pd1 alloy was found to keep a mixed glassy + Al phases in the relatively large ribbon thickness range up to about 200 μm for the melt-spun ribbon and in the diameter range up to about 1100 μm for the wedge-shaped cone rod prepared by injection copper mold casting. The glassy phase in the Al-based alloy has a unique crystallization process of glass transition, followed by supercooled liquid region, fcc-Al + glass, and then Al + Al3Y + Al9 (Co, Fe)2 + unknown phase. It is also noticed that the primary precipitation phase from supercooled liquid is composed of an Al phase instead of coexistent Al + compound phases, being different from the crystallization mode from supercooled liquid for ordinary Al-based glassy alloys. In addition, it is noticed that the mixed Al and glassy phases are extended in a wide heating temperature range of 588–703 K, which is favorable for the development of high-strength nanostructure Al-based bulk alloys obtained by warm extrusion of mixed Al + amorphous phases. The Vickers hardness is about 415 for the glassy phase and increases significantly to about 580 for the mixed Al and glassy phases. The knowledge of forming Al + glassy phases with high hardness in the wide solidification and annealing conditions through high stability up to complete crystallization for the multicomponent alloy is promising for future development of a high-strength Al-based bulk alloy.

High strength Mg94Zn2.4Y3.6 alloy with long period stacking ordered structure prepared by near-rapid solidification technology

To obtain high strength for near-rapid solidification (NRS) magnesium alloys, the microstructures and mechanical properties of the Mg94Zn2.4Y3.6 (at%) alloys, which were prepared by ordinary and injection copper mold casting (ICMC), respectively, were investigated comprehensively. It has been shown that the microstructure of ICMC Mg94Zn2.4Y3.6 alloy possesses the far-away-from equilibrium feature of NRS materials, which is composed of refined α-Mg grains with supersaturated Y and Zn, fine network-like long-period stacking-order (LPSO) phases and a few of Mg24Y5 particles. The interface between LPSO phase and α-Mg matrix is semi-coherent with the orientation relationship of [0002]α//[112¯0]LPSO, (101¯0)α//(0002)LPSO. The ICMC alloy exhibits enhanced mechanical properties with the ultimate tensile strength and elongation up to 355MPa and 7% at room temperature, respectively, and with the ultimate tensile strength of 302MPa at 150°C. It can be concluded that the strengthening mechanisms of this ICMC alloy are attributed to the grain refinement, the solid solution effect, the secondary phase strengthening and the crystalline boundaries strengthening.

Enhanced glass-forming ability and mechanical properties of Zr65Cu17.5Al7.5Ni10 metallic glass by adding Fe

The main objective of the paper is to improve the plasticity and reduce the toxicity of the known Zr65Cu17.5Ni10Al7.5 alloy. A series of rod samples with diameter of 2mm Zr65Cu17.5Al7.5Ni10–xFex (x=0, 2, 4, 6, 8, 10) were prepared by injection copper mold casting method. Appropriate addition of Fe can enhance GFA of the base alloy significantly. In addition, compared with the base alloy revealing no plastic deformation, partial substitution of Ni by Fe can also improve the compressive plasticity (εp) of alloys effectively. The enhanced plasticity of alloys can be attributed to the positive heat of mixing between Fe and Cu atoms. Alloy with 6% Fe exhibits the relatively good comprehensive properties, as a result of an excellent combination of both good GFA (ΔTx=81K) and remarkable plasticity (εp=6.2%). Zr65Cu17.5Fe10Al7.5 metallic glass is environmentally friendly and has large deformation plasticity, making it a promising candidate for engineering applications.

Mechanical properties and structure of rapidly solidified bulk Fe89 − xHf4Ta1Cu1Gd1SixB4 (x = 0–15) and Fe74Hf4Ta1Cu1Gd1LaySi15 − yB4 (y = 7) alloys

Authors investigated mechanical properties of microcrystalline Fe89−xHf4Ta1Cu1Gd1SixB4 (x=0–15) and Fe74Hf4Ta1Cu1Gd1LaySi15−yB4 (y=7) alloys obtained by copper mold injection casting to a form of rods, 3mm in diameter. Structure of the samples was analyzed by Cu K-α powder X-ray diffractometry and the unit cell parameters of identified h-Fe2Hf0.8Ta0.2 (C14 Laves), fcc-Fe16Hf6Si7 (D8a) and bcc-Fe phases were calculated. The study revealed that ascending Si content leads to reduction in values of both unit cell parameters of C14 phase in the alloys studied while causes the expansion of D8a lattice; decrease in secondary dendrite arm spacing in the middle of the rods; stepwise improvement of yield and compressive strength at the expense of plastic deformation region, what was attributed to the precipitation of C14 Laves/D8a in the interdendritic regions of bcc-Fe; decrease in flexural strength with no effect on deflection-at-yield and exponential increase in hardness of the studied alloys. There is also clear correlation between unit cell volume of fcc-Fe16Hf6Si7 phase, yield and compressive strength on Si content. For the alloys with x=0–13, relation between yield strength and Vickers hardness was described with logarithmic function. It was found, that the lattice expansion of bcc-Fe and, in lesser extent, C14 Laves phase is correlated with the value of bending modulus in the whole composition range.

Kinetic analysis of the non-isothermal crystallization process, magnetic and mechanical properties of FeCoBSiNb and FeCoBSiNbCu bulk metallic glasses

The crystallization kinetics of [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 and {[(Fe0.5Co0.5)0.75B0.2Si0.05]0.96Nb0.04}99.5Cu0.5 bulk metallic glasses were evaluated using differential scanning calorimetry under non-isothermal condition. The fully glassy rods with diameters up to 2 mm were obtained by copper mold injection casting. Both glasses show good thermal stability, but the addition of only 0.5% Cu completely changes the crystallization behavior. The average activation energy required for crystallization decreases from 645 kJ/mol to 425 kJ/mol after Cu addition. Upon heating, the Cu-free alloy forms only the metastable Fe23B6 phase. In contrast, two well-separated exothermic events are observed for the Cu-added bulk glassy samples. First, the (Fe,Co) phase nucleates and then (Fe,Co)2B and/or (Fe,Co)3B crystallize from the remaining glassy matrix. The Cu-added alloy exhibits a lower coercivity and a higher magnetic saturation than the base alloy, both in as-cast as well as in annealed condition. Besides, the Cu-added glassy sample with 2 mm diameter exhibits a maximum compressive fracture strength of 3913 MPa together with a plastic strain of 0.6%, which is highest plastic strain ever reported for 2 mm diameter ferromagnetic bulk metallic glass sample. Although Cu addition improves the magnetic and mechanical properties of the glass, it affects the glass-forming ability of the base alloy.

Strain Mapping of Indented Zr-Based Bulk Metallic Glass Using Nano-Diffraction

The state-of-the-art nano-diffraction technique available at the P06 beamline of the synchrotron radiation source PETRA III was used to observe the strain distribution induced within bulk metallic glass by nano-indentation. Bulk metallic glass (BMG) with nominal composition Zr52.5Ti5Cu17.9Ni14.6Al10 at.% was prepared by conventional copper mold injection casting. Using the Berkovich indenter a series of indents forming a line was introduced on to the polished surface of the BMG sample. It has been shown that spatially resolved matrix scans with a nanometer sized beam (600 × 600 nm2) can identify positions of the indents and quantitatively describe the strain state after nano-indentation.

Phase Selection in Sub-Rapidly Solidified Au-20Sn Alloys

The sub-rapidly solidified Au-20Sn eutectic alloys were prepared by four different solidification pathways, such as, graphite mold conventional casting, graphite mold injection casting, copper mold injection casting, and water-cooled copper mold suction casting. The precipitating sequences of competing primary phases of sub-rapidly solidified Au-20Sn alloys with four different cooling rates were investigated. The results show that phase selection process is related to the cooling rates during sub-rapid solidification process. The primary ζ'-Au5Sn phase with developed dendrites precipitate at low cooling rate (2.4×10−4.2×102K/min) and the morphologies of the primary ζ'-Au5Sn change to rosette-like at higher cooling rate (9.0×103K/min). While the cooling rate reaches to 3.5×104K/min, the primary ζ'-Au5Sn phase can be suppressed but δ-AuSn phase will precipitate prior to the ζ'-Au5Sn phase. On the basis of the classical nucleation theory and transient nucleation theory, the process of competitive nucleation between the ζ'-Au5Sn phase and the δ-AuSn phase were analyzed for sub-rapid solidified Au-20Sn alloy. The theoretical calculations are consistent with the experimental investigations.

Magnetic properties, microstructure and corrosion behavior of Nd10Y1Fe85−xNb3.5Ti0.5Bx (x = 14–22) and Nd10Y1Fe69Nb3.5M0.5B16 (M = Ti, Zr, Cr, Mo) bulk nanocrystalline magnets

The bulk nanocrystalline magnets of Nd10Y1Fe85−xNb3.5Ti0.5Bx (x=14–22) and Nd10Y1Fe69Nb3.5M0.5B16 (M=Ti, Zr, Cr, Mo) in rod form with a diameter of 1.5mm were prepared by copper mold injection casting. The magnetic properties, microstructure and corrosion behavior of bulk magnets have been studied. It is shown that the glass forming ability of alloy is obviously improved with increasing the B content. For the Nd10Y1Fe85−xNb3.5Ti0.5Bx (x=14–22) alloys, the optimal magnetic properties of Br=6.0kG, iHc=7.8kOe and (BH)max=6.7MGOe can be achieved when x=16, although the sample of x=22 exhibits better corrosion resistance than the sample of x=16. For the Nd10Y1Fe69Nb3.5M0.5B16 (M=Ti, Zr, Cr, Mo) alloys, the sample of M=Zr exhibits the best magnetic energy product of (BH)max=7.0MGOe, with Br=6.3kG and iHc=8.2kOe. While, the highest intrinsic coercivity of iHc=8.8kOe, with Br=5.6kG and (BH)max=5.8MGOe is obtained in the sample of M=Mo. The electrochemistry analysis shows that the Zr-doped sample has the best corrosion resistance among the M-doped alloys. The thermogravimetric analysis reveals that the oxidation rates of bulk magnets are significantly enhanced when the temperature is above 350°C, and the Ti-doped sample has the best antioxidant ability among the M-doped alloys.

Preparation and Characterization of Fe-Based Metallic Glasses with Pure and Raw Elements

Amorphous alloys with a composition (at.%) Fe48Cr15Mo14C15B6Y2 were prepared by using either pure elements (alloy B1) or a commercial AISI430 steel as a base material (B2). When prepared from pure elements, alloy (B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in an air atmosphere. In the case of alloy B2, prepared by using commercial grade raw materials, rods of 2 mm diameter are obtained. Ribbons (B1 and B2) of width 5 mm and thickness about 30 μm are prepared from the arc-melted ingots using a single roller melt spinner at a wheel speed of 40 m/s. The thermal and structural properties of the samples are measured by a combination of differential scanning calorimetry (DSC), x-ray diffraction and scanning electron microscopy. Chemical compositions are checked by energy dispersive spectroscopy analysis. X-ray diffraction and scanning electron microscopy observations confirm that an amorphous structure is obtained in all the samples. A minor fraction of crystalline phases (oxides and carbides) is detected on the as-cast surface. Values of hardness and Young modulus were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and the partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

High coercivity (Nd8Y3)–(Fe62Nb3Cr1)–B23 magnets produced by injection casting

High coercivity (Nd8Y3)–(Fe62Nb3Cr1)–B23 magnets in rods have been produced by copper mold injection casting. Magnetic properties, microstructure, and phase evolution in the as-cast and annealed states have been presented and discussed. The (Nd8Y3)–(Fe62Nb3Cr1)–B23 alloys show hard magnetic properties in the as-cast state. Annealing induces ideal microstructure containing magnetically hard and soft phases with hard/soft volume ratio of 73/27. Exchange coupling between magnetically hard (Nd,Y)2Fe14B phase and soft α-Fe (Fe3B) phase leads to excellent hard magnetic properties. Highest coercivity of 1230 kA/m in (Nd8Y3)–(Fe62Nb3Cr1)–B23 magnet originates from the large amount of hard phase with high magnetocrystalline anisotropy, formation of thin grain boundary phase and refinement of magnetic grains. Nb and Cr doping modify the magnetic phases. Annealed magnetic rods with a diameter of 2 mm and 36 mm in length demonstrated the maximum magnetic properties i.e., iHc of 1230 kA/m, Br of 0.49 T, and (BH)max of 45.6 kJ/m3.

Preparation and characterization of Fe-based bulk metallic glasses in plate form

Amorphous alloys with composition (at%) Fe48Cr15Mo14C15B6Gd2 (alloy A) and Fe48Cr15Mo14C15B6Y2 (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2mm and variable lengths between 10 and 20mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2mm diameter were obtained.X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856K for alloy A and 841K for alloy B1, and an onset crystallization temperature of 887K for alloy A and 885K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed.Values of hardness (∼13GPa) and the Young modulus (∼180GPa) were measured by nanoindentation for both the alloys.The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.