Alloy Binder Research Articles

Research of the melting zone of the relit – cupronicel composite alloy when surfacing metallurgical equipment parts using the furnace method

With the furnace surfacing method, a composite alloy is obtained, consisting of reinforcing particles of tungsten and cupronickel carbides, which, after exposure to the melting temperature of the binder alloy, form a wear-resistant layer on the surface being hardened. It has been established that in the zone of connection of the composite alloy relit – cupronickel with the steel surface of the part, in the absence of conditions that guarantee auto-vacuum cleaning of the surface from oxides, an interlayer with an imperfect crystal structure is formed, which leads to delamination of the deposited alloy. It has been experimentally shown that the use of additional control for the gas tightness of the surfacing space makes it possible to improve the quality of the deposited surface when furnace hardening of metallurgical equipment parts with the composite alloy relit – cupronickel.

The microstructure evolution and mechanical properties of WC-cu-10Ni-5Mn-3Sn cemented carbides containing NbC prepared by pressureless melt infiltration

WC-based cemented carbides with different contents of NbC (0, 0.6, 0.8, 1.0, 1.2, and 1.4 wt%) are prepared via pressureless melt infiltration at 1200 °C for 1.5 h. Microstructure evolution regularity of WC-based cemented carbide is investigated to establish the effect of NbC addition and microstructure peculiarities on mechanical properties (flexural strength, hardness, and impact toughness) of final product. Experimental results reveal that NbC firstly dissolves in binder alloy during melt infiltration, which slows down dissolution-precipitation reaction of WC, thus refining WC grains. With the increase in NbC content, average WC grain size shows varying trend, achieving the minimum (3.779 μm) at NbC addition of 1 wt%. When NbC is added in smaller amounts, Nb is mainly distributed throughout binder alloy. With the increase in NbC content, Nb elements tend to form aggregates and attach to WC particle boundaries. Some WC and NbC also decompose under experimental conditions. At NbC addition greater than 1 wt%, decomposition products (Nb, W, and C) combine with other elements in binder phase to form new phases such as (Nb,W)C, Ni2W4C, Nb2C, and Nb4Ni2C. These phases further act as bridges for WC grain coarsening. Meanwhile, excessive NbC is detrimental to mechanical properties of the alloy. With the increase in NbC content, hardness and flexural strength of the alloy increase and then decrease, reaching the maximum values of 93.4 HRA and 1808.786 MPa, respectively, at 1 wt% NbC addition. In turn, impact toughness of the alloy shows consistently downward trend. Therefore, changes in mechanical properties of WC-based cemented carbides are mainly related to WC grain size, the appearance of new phases in binder phase, and their morphology.

High-Hardness Cemented Carbide With Nickel-Tungsten Alloy Binder

High-Hardness Cemented Carbide With Nickel-Tungsten Alloy Binder

Wear behavior of functionally graded cemented carbides with CoNiFeCr multi-principal-element alloy binder

The good combination of mechanical and wear properties for cemented carbides is crucial. In this work, the wear behavior of functionally graded cemented carbide (FGCC) and non-graded cemented carbide (CC), with CoNiFeCr multi-principal-element alloy (MPEA) binder, has been investigated by performing sliding wear tests and composition characterization. The results showed that compared with CC, FGCC had higher hardness, stronger fracture toughness, better wear performance, and similar TRS. FGCCs exhibited lower wear rates (3.44 × 10−7–6.95 × 10−6 mm3/(N m)) and coefficients of friction (COFs) (0.27–0.39) than CCs from RT to 600 °C due to mitigation of multiple risks caused by binder removal, fragmentation and pull-out of WC grains, high-temperature oxidation and softening. In the low-temperature wear stage, the MPEA binder underwent dynamic recrystallization (DRX) and twinning deformation before removing from the surface. The binder removal caused dislocation pile-ups and stacking faults (SFs) to form under high stress, resulting in fragmentation and pull-out of WC grains. The low-temperature wear was dominated by abrasive wear and adhesive wear, with a low wear rate and a high and unstable COF. In the high-temperature wear stage, initial pitting oxidation of WC grains generated many subgrain boundaries, reducing heat transfer and exacerbating oxidation, resulting in an oxide layer enriched with WO3, MxOy, and MWO4. High-temperature wear was dominated by oxidation wear and high-temperature softening, with a high wear rate and a low and smooth COF. The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr, but also a new approach for the preparation of cemented carbides with high wear resistance.

Effect of Cr3C2 Addition on Microstructure and Mechanical Properties of WC-CoNiFe Cemented Carbides

In traditional cemented carbides, Co is mainly used as a binder. Recently, replacing Co with medium- to high-entropy alloys has shown significant improvements in hardness, fracture toughness, high-temperature oxidation resistance, and corrosion resistance, making it a research focus globally. Both the typical grain refiner Cr3C2 and medium- to high-entropy alloy binders affect the WC grain size in cemented carbides. This study investigates the synergistic grain refinement mechanism of Cr3C2 and medium- to high-entropy alloy binders on WC grains and their impact on the microstructure and mechanical properties of cemented carbides. The results show that increasing the Cr3C2 addition refined WC grains in the WC-CoNiFe alloy, increased coercivity, and enhanced hardness, with transverse rupture strength first increasing and then decreasing. The alloy achieved optimal performance at 0.6 wt.%Cr3C2, with a hardness of 91.25 HRA and transverse rupture strength of 3883.2 MPa.

On the fcc to hcp transformation in a Co-Ru alloy: Variant selection and intervariant boundary character

Ru is a common addition to the Co-binder in WCCo hardmetals for advanced cutting tool applications. Internal Co-Co interfaces control many properties such as hot-hardness, toughness, and creep resistance. Hence, phase transformations determining the internal interface character can be harnessed to achieve superior properties. We investigate the γ (face-centred cubic) to α (hexagonally closed packed) martensitic phase transformation of a model Co-Ru binder alloy. We describe the crystallography of γ to α phase transformations and the resulting α/γ and α/α interface character distributions. The stabilisation of the γ-phase results in the formation of low energy (0 0 0 1) α/γ interphase boundary planes. Preferred formation of α/α intervariant and twin-related boundaries with symmetrical tilt configurations are also observed. We discuss how crystallographic constraints of the transformation promote the formation of grain boundary planes other than those of the lowest energy configurations.

The effect of carbide decomposition and carbon loss on the steady state composition of WC-Cr3C2-Ni composite coatings at 900 °C.

The steady-state composition and microstructure of 42 wt% WC-42 wt% Cr3C2–16 wt% Ni coatings sprayed under “low”, “medium” and “high” thermal input conditions was explored following treatment at 900 °C for up to 30 days. None of the coatings achieved thermodynamic equilibrium compositions. Attempts at compensating for mechanisms of bulk carbon loss and selective carbon loss from the dissolution phases alone, were both unsuccessful in predicting the steady-state compositions based on equilibrium phase diagrams. The low thermal input HVOF coating underwent recovery of the dissolved Cr3C2 phase to form an interconnected, two-phase Cr3C2 + Ni-alloy matrix surrounding the retained WC grains, which did not achieve thermodynamic equilibrium with the precipitating phases. The high carbide dissolution plasma ArH2 coating generated a homogeneous distribution of metallic and carbon elements such that the metal: carbon ratio exceeded 1:1, favouring the formation of (W,Cr)2C. The remaining material formed (Cr,W)3C2 within a Ni(Cr,W) alloy binder. Chromium stabilised the (W,Cr)2C phase such that it did not decompose into W + WC, as predicted in the WC system. The plasma ArHe response was a mix of these mechanisms. A distinctive feature of the heat-treated coatings was the lack of significant grain growth, with submicron carbide grains retained out to 30 days at 900 °C.

WC-based cemented carbide with NiFeCrWMo high-entropy alloy binder as an alternative to cobalt

In the current work, a nanostructured NiFeCrWMo high entropy alloy (HEA), synthesized by mechanical alloying, was used as the alternative binder phase for substituting Co to fabricate WC–HEA cemented carbides by electron–beam sintering (EBS). The microstructure and mechanical properties of initial powder mixtures and sintered samples were studied using X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), indentation technique and compression tests. NiFeCrWMo HEA does not have direct interaction with WC, but at the boundaries between WC and HEA particles (Ni, Fe, Cr)xWyCz complex carbide is formed as result of reduction processes during sintering. The results show that WC–HEA cemented carbide has better performances than the commercial WC–8Co-cemented carbide prepared by EBS. The NiFeCrWMo HEA binder significantly slows down the growth of WC grains due to the sluggish diffusion effect and the formation of a small amount of complex carbide, and, compared to Co, improves the mechanical properties, provides an excellent combination of microhardness (18.9 ± 0.4 GPa) and fracture toughness (11.4 ± 0.3 MPa m1/2). Therefore, the NiFeCrWMo high entropy alloy can potentially become a binder for WC cemented carbides.

Influence of thermomechanical treatment on the formation of the structure in dispersed-reinforced aluminum alloy-based metal composite materials

The study explored various facets of the structure of dispersed-reinforced aluminum alloy-based metal composite material (MCM) under different modes of thermomechanical treatment. Replacing traditional structural materials with MCM provides manufacturers with an opportunity to achieve higher levels of engineering superiority. The ability to choose composition, modify primary component ratios, and employ a range of MCM manufacturing techniques allows for precise tuning of the material's strength, rigidity, temperature range, and other physical and mechanical properties. Two prevalent technologies for crafting dispersed-reinforced aluminum alloy-based MCM exist: liquid-phase and powder technologies. Liquid-phase methodology entails merging the reinforcing component into the binder alloy's melt, followed by crystallization. This process guarantees the dispersion and fixation of reinforcing particles within the binder volume. In contrast, powder technology involves simultaneous processing of primary component powders in high-energy mills, with subsequent amalgamation of the resultant composite granules via pressure molding. The chief aim of thermomechanical treatment lies in yielding blanks that closely mimic the final product's geometry and reshaping the deformable material's structure to heighten its strength properties. Powder technology was employed to fabricate monolithic composite material samples. Their structures were analyzed, accompanied by tests to ascertain density and strength parameters of the MCM at room temperature. Consequently, dispersed-reinforced aluminum alloy-based MCM possessing a uniform structure, density exceeding 99.0 % of the theoretical value, and elevated mechanical attributes: σu = 300÷305 MPa and E = 87÷95 GPa, were successfully produced.

Oxidation behavior of functionally graded cemented carbides with CoNiFeCr multi-principal-element alloy binder

The oxidation behavior of the WC-CoNiFeCr functionally graded cemented carbide (FGCC) has been investigated by isothermal oxidation and composition characterization. The results showed that the oxidation of cemented carbide was closely related to the oxidation temperature and oxidation time, and the oxidation of different elements had a clear sequential order. The Cr element was first selectively oxidized to Cr2O3, followed by the oxidation of other composing elements of the multi-principal-element alloy (MPEA) binder to MxOy and MWO4. The WC was then oxidized to WO3, and WO3 and MxOy were thereafter reacted to form MWO4. The binder composition, structural distribution, and WC grain size were the three key factors that affected the oxidation resistance of the cemented carbides. Fine-grained and graded cemented carbides, with CoNiFeCr MPEA binder, had the highest anti-oxidation properties. The FGCC showed lower oxidation of the binder at 600 °C, a denser MWO4 distribution at 700 °C, and a smaller volume expansion at 800 °C, as compared with the non-graded cemented carbide (CC). Compared with the coarse-grained cemented carbide, the fine-grained cemented carbide had more grain boundaries between the WC and the binder, which resulted in a denser distribution of the binder oxides. WC-20CoNiFeCr had a higher energy barrier for the oxidation reaction and more stable oxidation products than WC-20Co. The results did not only provide theoretical guidance for the understanding of the anti-oxidation mechanism of WC-CoNiFeCr, but they also expanded a new approach for the preparation of cemented carbides with high oxidation resistance.

TiCN Cermets with MnFeCoNiCu High Entropy Alloy Binder

Cermets are composites of a TiCN hard phase and a metal binder, typically a mixture of Co and Ni. They offer excellent combinations of hardness and fracture toughness as well as bending strength. Due to the current classification of both Co and Ni as CRM as well as CMR there is interest that their use shall be limited and their amount within cermets reduced. Within this study, a novel high entropy alloy-based metal binder system, comprising only elements that are not strong oxide or carbide formers is investigated with regard to their mechanical and microstructural properties they offer in TiCN-based cermets. Within the investigated equimolar MnFeCoNiCu composition, small Cu precipitations are found after sintering. Due to this, the Cu content was systematically reduced, and the maximal solubility estimated at which still a full solid solution occurs. With an optimized Cu content, dense cermets with a single FCC binder phase and with hardness values of up to 1213 HV30 and fracture toughness values of 14.8 MPa·m1/2 could be achieved.

The microstructure and mechanical properties of Ce2O3 reinforced WC-Cu-10Ni-5Mn-3Sn-1.5TiC cemented carbides fabricated via pressureless melt infiltration

Microstructure and mechanical properties of WC-Cu-10Ni-5Mn-3Sn-1.5TiC cemented carbides fabricated by pressureless melt infiltration at 1200 °C for 90 min with different Ce2O3 contents (0 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, and 1.0 wt%) were investigated. Ce2O3 accelerated the decomposition and dissolution of WC. The melt infiltration reaction products of high carbon solid solution, such as W, Ni2W4C, and (Ti,W)C1-X are precipitated in binder alloys. High carbon solid solution gradually decreased or even disappeared, and W, Ni2W4C, and (Ti,W)C1-X seemed to grow with the increase of Ce2O3 contents. Considering the influence of decomposition and dissolution of WC and the formation of new phases, the size of WC particles decreased while the surface morphology of WC slowly changed from round and blunt to sharp-angle shaped, and the contiguity value of WC particles first decreased and then increased. The changes in microstructural properties of cemented carbides as a function of Ce2O3 inevitably led to the change in mechanical properties. The sample with 0.4 wt% Ce2O3 additions had the highest hardness (94.8 HRA). The highest values of impact toughness and TRS in 0.6 wt% Ce2O3 cemented carbides were 7.15 J cm−2 and 1977.8 MPa, respectively.

High temperature oxidation behavior of spark plasma sintered WC-CoCrFeNiAl hard alloys

The oxidation behavior of WC-CoCrFeNiAl hard alloy in air environment under 600–800 °C was studied and compared with that of WC-Co hard alloy. The results showed that the oxidation behavior of WC-CoCrFeNiAl hard alloy was controlled by the chemical reaction at the interface of matrix and oxide layer. The oxidation resistance of WC-CoCrFeNiAl hard alloy was significantly better than that of WC-Co hard alloy, and the high-temperature oxidation gain at 800 °C was only 60% of that of WC-Co hard alloy. The oxidation resistance of WC-CoCrFeNiAl hard alloy increases with the increase of high entropy alloy binder content, and the mass gain of WC-20CoCrFeNiAl hard alloy is only 14% of that of WC-5CoCrFeNiAl hard alloy. The excellent oxidation resistance of CoCrFeNiAl high entropy alloy improving the oxidation resistance of WC-CoCrFeNiAl hard alloys.

Effect of carbon and tungsten content on the phase equilibria, microstructure, and mechanical properties of (Nb,W)C–Ni cermets

AbstractWith the assistance of thermodynamic simulation, the NbC–Ni based cermets with different W and C additions were designed and sintered in liquid state at 1390°C for 90 min in vacuum. By controlling the carbon and tungsten content, (Nb,W)C–Ni based cermets were prepared with varied phase constitution, microstructure, and mechanical properties. The microstructure, composition of phases, grain size, and equilibrium phases were investigated using scanning electron microscopy, electron probe microanalysis, EBSD, and X‐ray diffraction. The simulation reasonably predicted the experimentally observed phase constitutions. Depending on the additions, detailed analysis indicated that the cermets were composed of either a combination of cubic (Nb,W)C solid solution and Ni alloy binder or with an additional carbon‐deficient phase. Furthermore, mechanical analysis showed a strong dependence of its mechanical properties (Vickers hardness, indentation toughness, and flexural strength) on the phases and NbC grain size.

Improved interfacial bonding of c-BN with Ni-based binder alloys: Fast searching of alloying elements based on first principles

Improved interfacial bonding of c-BN with Ni-based binder alloys: Fast searching of alloying elements based on first principles

Study on Effect of High-Entropy Alloy Binder on Microstructure and Properties of WC Cemented Carbide Doped with Rare Earth Oxide

The AlCoCrFeNi powder was added to WC powder as a binder and Y2O3/ZrO2 was doped by the wet chemical method as grain-growth inhibitors. The WC-Y2O3-ZrO2-10AlCoCrFeNi composite powders were sintered by spark plasma sintering to obtain an alloy. The microstructure and properties of the cemented carbide were studied. The result showed that the rare-earth-oxide (Y2O3/ZrO2)-refined grain size of the alloy and the high-entropy alloy binder provided the alloy with better hardness and toughness. The AlCoCrFeNi diffused slowly between the WC grains because of a delayed diffusion effect and Cr having a low affinity for the WC matrix. During the dynamic process of the WC particles’ dissolution and precipitation growth, the Fe, Co, and Ni that had a better affinity for the WC matrix diffused and distributed more smoothly, which increased the strength and toughness of the alloy. When the temperature of the SPS sintering was 1250 °C, the WC-Y2O3-ZrO2-10AlCoCrFeNi cemented carbide had the best properties, which was a Vickers hardness of 1888.14 HV and a fracture toughness of 14.76 MPa·m1/2.

Microstructure and mechanical properties of hot isostatic pressed tungsten heavy alloy with FeNiCoCrMn high entropy alloy binder

Microstructural development and mechanical properties of tungsten heavy alloy, WHA, with FeNiCoCrMn high entropy alloy, HEA, binder were investigated and compared to conventional WHA using Fe–Ni binder. Both WHAs, with HEA and conventional Fe–Ni binders, were fabricated by hot isostatic pressing at a temperature of 1450 °C in an argon environment. Scanning electron microscopy revealed that WHA with HEA and conventional binders possessed uniform and well-refined microstructures. Energy dispersive spectroscopy and X-ray diffraction, XRD, spectroscopy validated the formation and composition of HEA, existing as a skeletal network surrounding tungsten grains. HEA binder exhibited an overall increase of 42% in micro Vickers hardness values. Furthermore, hardness values of the tungsten heavy alloy were also seen to rise when fabricated with HEA binder. However, WHA sample with HEA binder was seen to undergo faster strain hardening and a premature failure, leading to lower values of ultimate strength and reduced ductility.

Microstructural Evolution of Diamond-Based Composites at High Temperature and High Pressure.

Improving the toughness of diamond composites has become an industrial demand. In this work, Co50Ni40Fe10 multi-element alloy was designed as binder for diamond-based composites prepared by high temperature and high pressure (HTHP). Two methods of mixing-sintering and infiltration-sintering were used to prepare diamond-based composites with different diamond contents. The phase diagrams of Co-C and Co50Ni40Fe10-C at 6 GPa were calculated by Thermo-Calc. The results show that Co50Ni40Fe10 multi-element alloy promotes the sintering of diamond powder than element Co. The transverse rupture strength (TRS) of sintered diamond with Co50Ni40Fe10 (Co50Ni40Fe10-75 vol% diamond) is higher than that of Co-Comp (Co-75 vol% diamond). The TRS of polycrystalline diamond (PCD) with Co50Ni40Fe10 alloy binder is up to 1360.3 MPa, which is 19.2% higher than Co-PCD. Compared with Co, using Co50Ni40Fe10 as binder results in a less metal residue in PCD, while the metal cluster area is smaller and the metal distribution is more uniform.

Magnetic Properties and Microstructure of Ce-Cu-Al Low Melting Alloy Bonding Sm2Fe17N3 Magnet Fabricated by the Hot-Pressing Method

Sm2Fe17N3 compounds, having excellent intrinsic magnetic properties, are prone to decomposition at high temperatures; thus, a low melting point metal binder is the key to prepare high performance bulk magnets at low temperatures. In this paper, a new low melting point alloy Ce72Cu28-xAlx was used as the binders, and high-performance Ce-based alloy bonding Sm2Fe17N3 magnets were realized by the hot-pressing method. The experimental results demonstrated that the content of Al in the Ce-based alloys had an important influence on the performance of the magnets. High performance Sm-Fe-N bonded magnets with remanence of 10.19 KGs and maximum magnetic energy product of 21.06 MGOe were achieved by using 5 wt.% Ce72Cu22Al6 alloy as a binder. At the same time, it was found that the Ce72Cu28-xAlx alloy has a lower density and better bonding effect than the common Zn binder. Its bonding magnets still have higher performance even with extremely high oxygen content. Therefore, Ce72Cu28-xAlx alloy with low melting point is a promising new rare earth-based alloy binder. If the oxygen content of the alloy powders could be reduced, higher performance Sm2Fe17N3 bonded magnets can be prepared.

Microstructure and mechanical behavior of functionally graded cemented carbides with CoNiFeCr multi-principal-element alloy binder

In this work, functionally graded cemented carbides (FGCCs) with CoNiFeCr multi-principal-element alloy (MPEA) binder were prepared by pre-sintering and carburizing. The microstructure and mechanical behavior of WC-CoNiFeCr FGCCs with different carbon contents obtained at different carburization temperatures were studied. The results showed that a higher carbon content simultaneously accelerated the diffusion rate of carbon and increased the diffusion channel of carbon. The FGCC with a carbon content of 4.55% obtained at a carburizing temperature of 1450 °C exhibited the thickest gradient layer and the highest extreme hardness difference, TRS, and fracture toughness. Moreover, as the thickness of the gradient layer increased, the fatigue sensitivity of FGCCs enhanced, approaching the characteristics of metallic materials.