Ti Phase Research Articles

Microstructural evolution and mechanical properties of Al-4Ni-0.4V alloyed with Zr and Ti at elevated temperatures

The influence of Zr and Ti alloying on the microstructural evolution and mechanical properties of an Al-4Ni-0.4V alloy at elevated temperatures was investigated. The results showed that the coarsening rate of the eutectic Al3Ni phase in the Al-4Ni-0.4V-0.2Zr-0.2Ti alloy decreased from 21.1 nm3/s in the Al-4Ni-0.4V alloy to 7.4 nm3/s after annealing at 350 °C for 0 h to 120 h. The tensile strength, yield strength, and elongation at room temperature of the annealed Al-4Ni-0.4V-0.2Zr-0.2Ti alloy (350 °C, 8 h) were 181 MPa, 108 MPa, and 27.2 %, respectively. After tensile test at 350 °C, these values of the annealed Al-4Ni-0.4V-0.2Zr-0.2Ti alloy were 108 MPa, 72 MPa, and 29.8 %, respectively. Transmission electron microscopy results revealed the precipitation of the L12 ordered structure of the Al3M (M = Zr, V, Ti) phase, approximately 2 nm in size, in the α-Al after annealing. These phases exhibited excellent lattice matching with the α-Al and considerable precipitation strengthening. Segregation of Zr, V, and Ti elements at the α-Al/Al3Ni interface hindered Ni diffusion in the matrix, thereby reducing Al3Ni phase coarsening. Moreover, the Al3M phase precipitated at the interface exhibited favorable matching with the lattice planes of the α-Al and Al3Ni phase, which improved the thermal stability of the eutectic structure and the mechanical properties at elevated temperatures.

Investigation of Precipitation Behavior of a Novel Ni-Fe-Based Superalloy during High-Temperature Aging Treatment.

The precipitation behavior of a novel Ni-Fe-based superalloy developed for advanced ultra-supercritical (A-USC) coal-fired power plant applications during high-temperature aging treatment was investigated. The results showed that the major precipitates in the novel alloy were randomly distributed MC carbides, M23C6 carbides at grain boundaries, and the γ'-Ni3 (Al, Ti) phase in grain interiors after aging. MC remained relatively stable during both short-term and long-term aging. M23C6 quickly precipitated and exhibited a discrete distribution at grain boundaries during short-term aging, and partly developed into continuous films during long-term aging. After uniform precipitation, the shape of γ' remained spherical, and the size kept increasing with aging time according to the Lifshitz-Slyozov-Wagner (LSW) model. The hardness of the novel alloy was mainly associated with the precipitation behavior of γ'; as γ' gradually precipitated, the hardness steadily increased; after complete precipitation, as the size of γ' increased, the hardness first increased and then decreased, reaching the peak hardness when the average radius of γ' achieved the critical size. In addition, the novel alloy exhibited abnormal coarsening behavior at grain boundaries during both short-term and long-term aging. The coarsened grain boundaries were actually precipitate-free zones (PFZs) and the coarsened and elongated rod-like particles inside were identified as γ' precipitates. The mechanism of strain-induced grain boundary migration and the discontinuous coarsening reaction is proposed for the formation of PFZs. Furthermore, PFZs were considered to be potential crack sources during the creep rupture test, leading to earlier failure of the material.

Simultaneous improvement in mechanical properties, corrosion resistance and antibacterial properties of Ti-Ag sintered alloy with gradient nanostructure

Bioinert titanium (Ti) with antibacterial properties is crucial for bone implantations. Alloying Ag can endow Ti with antibacterial properties, while the mechanical, corrosion and antibacterial properties of Ti-Ag alloys are not satisfactorily balanced. In this work, Ti-x wt%Ag alloys (x=0.5, 1 and 3) were sintered by spark plasma sintering and then subjected to a surface mechanical rolling treatment (SMRT). The Ti-Ag alloys are composed of Ti, Ti-Ag and Ti2Ag phases. After SMRT, a gradient nanostructured (GNS) layer formed on the Ti-Ag surface, the mean grain size is ∼ 6 nm at the top surface and increases gradually with depth. The GNS layer endows Ti-Ag alloys with better wettability, higher nano-roughness and compressive residual stress. Incorporating limited Ag (≤1 wt%) in Ti can effectively enhance its mechanical (surface hardness, wear resistance and compressive strength) and anti-corrosion properties, and they can be further improved by forming a GNS layer. The antibacterial efficiency of Ti-Ag is positively proportional to Ag content, and they are significantly enhanced after surface nanocrystallization. The bacteriostatic mechanism is the synergistic interaction between leach Ag+ and nano Ag-containing phases of GNS Ti-Ag alloy. Both Ti-Ag and GNS Ti-Ag alloys possess good cytocompatibility, the GNS layer has the potential to encourage early differentiation of osteoblasts. The GNS Ti-Ag alloy with 1 wt% Ag has excellent comprehensive properties, which shows larger potential in orthopedic applications.

Strategic alloy design and processing for improved mechanical response in the Mo-Si-Ti system

This study focuses on the impact of off-eutectic microstructures on mechanical properties in ternary Mo-Si-Ti alloys, namely Ti-rich Mo-18Si-72Ti and Mo-16.5Si-72Ti, in relation to the well-researched eutectic, two-phase Mo-20Si-52.8Ti alloy. The microstructure of these alloys consists of a Ti-rich body-centered cubic solid solution (Ti,Mo,Si)ss and a hexagonal silicide phase (Ti,Mo)5Si3. Notably, the off-eutectic alloys exhibit remarkable compression ductility at 800 °C, distinguishing it from Mo-20Si-52.8Ti. The directionally solidified (DS) specimens of the Ti-rich alloys display higher strength compared to the arc-melted specimens. This enhanced strength is attributed to the multiple precipitation strengthening events present, despite the increase in the length scale of individual phases which further enhances the fracture toughness.

Distinct amorphization resistance in high-entropy MAX-phases (Ti, M)2AlC (M=Nb, Ta, V, Zr) under in situ irradiation

High-entropy materials have been proposed for applications in nuclear systems recently due to their outstanding properties in extreme environments. Chemical complexity in these materials plays an important role in irradiation tolerance since it significantly affects energy dissipation and defect behaviors under particle bombardment. Indeed, better resistance to irradiation-induced amorphization was observed in the high-entropy MAX (HE-MAX) phase (Ti, M)2SnC (M = V, Nb, Zr, Hf). However, in this work, we report an opposite trend in another series of HE-MAX phases (Ti, M)2AlC (M = Nb, Ta, V, Zr). It is demonstrated that the amorphization resistance is sequentially reduced as the number of components increases from single-component Ti2AlC to (TiNbTa)2AlC and (TiNbTaVZr)2AlC. These phenomena are verified through AIMD simulations and interpreted by analyzing the underlying properties combining lattice distortion and bonding characteristics through the first-principle calculation. By developing a machine-learning (ML) model, we can directly predict lattice distortion to screen HE-MAX phases with excellent resistance to irradiation-induced amorphization. We highlight that the elemental species plays a more crucial role in the irradiation tolerance of these MAX phases than the number of constituent elements. Knowledge gained from this study will enable an improved understanding of the irradiation tolerance in HE-MAX phases and other multi-elemental ceramics.

Some advances on precipitation hardening in Waspaloy: Critical review on the contribution of shear, Orowan and coherency mechanisms

The precipitation hardening mechanisms and their dependence on precipitate size (rp) and precipitate/matrix lattice misfit (δ) in γ'/γ systems were studied in nickel-base superalloy using micro-indentations experiments and theoretical models. Metallurgical states were characterized by TEM, SEM-EBSD, XRD and APT. For the precipitate size range studied (radius rp smaller than 110 nm), γ' precipitates are ordered spherical Ni3(Al,Ti) phase, the volume fraction remains relatively constant and equal to 20 % and lattice misfit δ is lower than 0.45 %. Prevalence of order strengthening by anti-phase boundary formation and Orowan bypassing was observed in various rp range, whereas chemistry and coherency strengthening were found insignificant in the nickel-base superalloy studied (Waspaloy®). Shearing by weakly coupled dislocations was dominant for fine precipitates, i.e. rp lower than 18 nm, shearing by strongly-coupled dislocations for an intermediate rp range, i.e. from 18 nm to 98 nm and Orowan bypassing for coarse precipitates with a rp larger than 98 nm.

Crystal plasticity-phase–field based analyses of interfacial microstructural evolution during dynamic recrystallization in a dual phase titanium alloy

In this study, an integrated crystal plasticity finite element–phase–field (CPFE–PF) model is developed to examine dynamic recrystallization (DRX) in a dual phase Ti alloy. The CP framework is coupled with PF by updating the free energy density with energy contributions due to plasticity. The evolution of grain boundaries through evolving non-conserved order parameters in the PF model is tracked using the Allen–Cahn equation. Nucleation is allowed to occur if the dislocation density exceeds a critical value. DRX is studied in various Ti morphologies such as an α−Ti single crystal containing a stiff elastoplastic particle, α-Ti bicrystals with low and high misorientation between grains, an α−β bicrystal and a globular α−β Ti structure with β phase at α−α interfaces. For an α−Ti bicrystal, a high misorientation facilitates the onset of DRX at the α−α interface at a significantly lower strain than the bicrystal with low misorientation. In an α−β bicrystal, DRX is only observed at the α−β interface. For the globular morphology, nucleation is observed at both α−β interfaces and inside α grains, which is consistent with previous experimental observations for a similar morphology. Nucleation inside α grains is explained by the correlation between SSD density and misorientation indicators such as KAM and GROD at the nucleus site. To correlate slip activity with nucleation propensity immediately prior to different nucleation events, the dislocation density, shear rate and Schmid factors on different slip systems are evaluated at nucleation sites.

Blistering Behavior of Beryllium and Beryllium Alloy under High-Dose Helium Ion Irradiation.

Beryllium (Be) has been selected as the solid neutron multiplier material for a tritium breeding blanket module in ITER, which is also the primary option of the Chinese TBM program. But the irradiation swelling of beryllium is severe under high temperature, high irradiation damage and high doses of transmutation-induced helium. Advanced neutron multipliers with high stability at high temperature are desired for the demonstration power plant (DEMO) reactors and the China Fusion Engineering Test Reactor (CFETR). Beryllium alloys mainly composed of Be12M (M is W or Ti) phase were fabricated by HIP, which has a high melting point and high beryllium content. Beryllium and beryllide (Be12Ti and Be12W) samples were irradiated by helium ion with 30 keV and 1 × 1018 cm-2 at RT. The microstructures of Be, Be12Ti and Be12W samples were analyzed by SEM and TEM before and after ion irradiation. The average size of the first blistering on the surface of Be-W alloy is about 0.8 μm, and that of secondary blistering is about 79 nm. The surface blistering rates of the beryllium and beryllide samples were also compared. These results may provide a preliminary experimental basis for evaluating the irradiation swelling resistance of beryllium alloy.

Microstructure and Wear Resistance of In Situ Synthesized Ti(C, N) Ceramic-Reinforced Nickel-Based Coatings by Laser Cladding.

In recent years, laser cladding technology has been widely used in surface modification of titanium alloys. To improve the wear resistance of titanium alloys, ceramic-reinforced nickel-based composite coatings were prepared on a TC4 alloy substrateusing coaxial powder feeding laser cladding technology. Ti (C, N) ceramic was synthesized in situ by laser cladding by adding different contents (10%, 20%, 30%, and 40%) of TiN, pure Ti powder, graphite, and In625 powder. Thisestudy showed that small TiN particles were decomposed and directly formed the Ti (C, N) phase, while large TiN particles were not completely decomposed. The in situ synthetic TiCxN1-x phase was formed around the large TiN particles. With the increase in the proportion of powder addition, the wear volume of the coating shows a decreasing trend, and the wear resistance of the surface coating is improving. The friction coefficient of the sample with 40% TiN, pure Ti powder, and graphite powder is 0.829 times that of the substrate. The wear volume is 0.145 times that of the substrate. The reason for this is that with the increase in TiN, Ti, and graphite in the powder, there are more ceramic phases in the cladding layer, and the hard phases such as TiC, Ti(C, N) and Ti2Ni play the role in the structure of the "backbone", inhibit the damage caused by micro-cutting, and impede the movement of the tearing point of incision, so that the coating has a higher abrasion resistance.

Sulphuric precipitates in novel titanium-based, sulphur-bearing bulk metallic glass – a BMG composite?

ABSTRACT New titanium-based metallic glasses containing sulphur as a key element have recently been developed and are the subject of ongoing research related to the effects of sulphur introduction into glass-forming alloy systems. Here we report on the formation of sulphuric precipitates during solidification of a Ti40Zr35Cu17S8 alloy and on the occurrence of secondary intermetallic compound crystallization starting in sulphur-depleted zones around the precipitates. The alloy is a promising metallic glass for use as a structural and biomedical material as it shows a high yield strength and good corrosion resistance paired with a low density. The role of sulphur for the glass formation in the Ti-Zr-Cu-S system is discussed and specimens quenched into different structural states are investigated by means of high-energy synchrotron diffraction and electron microscopy. The electron microscopic findings reveal that sulphuric precipitates precede the crystallization of an intermetallic (Ti, Zr)2Cu phase, which is the primary phase when sulphur is not present in the system and thus lead to a higher glass-forming ability. The sulphuric precipitates are found in specimens of various casting thickness and differ in their volume percentages depending on the size of the cast sample, while the secondary phase (Ti, Zr)2Cu crystallizes heterogeneously in the interfaces between the sulphuric precipitates and the local matrix.

Electromagnetic characterization of MAX phase and MXene in Ti–Al–C ternary system

The present paper set out to investigate the synthesis and electromagnetic characterization of Ti3AlC2 MAX phase and Ti3C2Tx MXene in Ti–Al–C ternary system. In this regard, Ti3AlC2 MAX phase was synthesized using mechanical milling process of TiC, Al, and Ti powder mixtures based on 2TiC–Al–Ti + xAl (x = 0, 0.25, 0.5, 0.75 and 1). The HF acidic etching was also employed to synthesize the Ti3C2Tx MXene. Structural and electromagnetic characterizations of the prepared samples were conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vector network analyzer. The obtained results point to the impossibility of the formation of Ti3AlC2 single-phase structure in stoichiometric system. In other word, development of the Ti3AlC2 single-phase structure is only possible in non-stoichiometric 2TiC–2Al–Ti system. The minimum reflection losses of the prepared Ti3AlC2 MAX phase was estimated to be around −30.73 dB at the matching frequency of 15.25 GHz. The results further revealed that the etching time affects electromagnetic behavior of the MXene. That is, an increase in the etching time brings about a change in the reflection loss (RL) from −24.17 to −5.69 dB within the frequency range of 1–18 GHz.

Corrosion behavior of SiC/Ti6Al4V titanium matrix composites fabricated by SLM

In this paper, Ti6Al4V alloy and Ti6Al4V-SiCw composites were formed by selective laser melting (SLM) and electrochemical corrosion experiments were carried out. The effects of different SiCw contents and solid solution aging heat treatment on the corrosion properties of the composites were systematically studied, and the corrosion mechanism of Ti6Al4V-SiCw composites was revealed. The results show that Ti6Al4V-1SiCw composites have better corrosion resistance than Ti6Al4V alloy. After solution and aging heat treatment at 1050 °C, Ti6Al4V-1SiCw composites have better corrosion resistance. The main reasons for the improvement of the corrosion performance of the composites are as follows: (i) The high-density grain boundaries formed by grain refinement of the composites have higher energy and are more likely to react to form a stable passivation film. (ii) The microstructure of Ti6Al4V-SiCw composites is equiaxed α phase, which is easier to form stable passivation film than metastable α′-Ti phase. (iii) The presence of ceramic particles makes more microcells formed in the titanium matrix, which promotes the formation of soluble [TiCl6]2- complexes. The formation of passivation film on the surface of Ti6Al4V-SiCw composites was accelerated.

A novel TaMoNbCrTi refractory high-entropy alloy produced by powder metallurgy

The process of mechanical alloying (MA) and spark plasma sintering (SPS) were employed to manufacture a novel TaMoNbCrTi refractory high-entropy alloy. The investigation concentrated on how variations in sintering temperatures resulted in microstructural differences, which in turn altered the mechanical properties of TaMoNbCrTi. A BCC-structured solid solution phase was formed as a result of the MA process. During further sintering, the Cr2(Ta, Nb) phase and Ti(O, N) phase precipitated from the BCC phase. The Cr2(Ta, Nb) phase volume fraction declined and transitioned from a reticular distribution to a dispersed distribution as the sintering temperature rose. Additionally, a considerable enhancement in the Ti(O, N) phase size was observed. Because of the uniform distribution of the fine precipitated phases, the TaMoNbCrTi alloy sintered at 1200 °C demonstrated superior mechanical properties.

Effects of spark plasma sintering and nanodiamond amount on titanium-nanodiamond composite properties

Titanium/nanodiamond (ND) mixtures were sintered using spark plasma sintering (SPS). Densification was studied for Ti + x wt% ND mixtures (where x = 2, 5, 10 and 15) to determine the optimized cycles. Ti/ND mixtures were then sintered under these optimized conditions achieving relative densities higher than 96 %. The SPS temperatures for the Ti + 2 wt% ND, Ti + 5 wt% ND, Ti + 10 wt% ND and Ti + 15 wt% ND mixtures were 1000 °C, 1050 °C, 1150 °C and 1150 °C, respectively. Numerical simulation by finite elements were used to check the thermal homogeneity in the sample and to determine the maximal temperature in the sample to ensure avoiding graphitization. The effects of ND on the Ti/ND mixtures were investigated. Microstructural characterizations reveal the presence of three different phases including a Ti phase, a non-stoichiometric TiCx solid phase and NDs located inside the TiCx grains. Indeed, NDs react with Ti to form the TiCx solid phase. However, a fast sintering with temperature below graphitization of diamond allows to keep nanodiamond structure into the Ti/ND mixtures. Hardness and electrical conductivity of the Ti/ND mixtures were measured. The results show that the higher the ND content, the more the hardness of the composite increases and the more the electrical conductivity decreases. Hardness increased from 340 HV to 1346 HV for Ti and the Ti + 15 wt% ND mixture, respectively. Electrical conductivity is reduced by a factor of three for the Ti + 15 wt% ND mixture relative to Ti which can be explained by the microstructure exhibiting fewer Ti grains in favor of the TiCx solid phase when ND content was increased in the composite.

New strategy in light-weight and ultrastrong Ti40Nb15Mo30(NbC)15 refractory complex concentrated alloy

Traditional refractory high-entropy alloys (RHEAs) generally exhibit a trade-off between high-temperature strength and light weight. In present work, a novel design strategy based on tailoring element distribution is proposed to achieve excellent high-temperature strength at a density lower than 7 g·cm-3. Specifically, a Ti40Nb15Mo30(NbC)15 composite was designed and prepared by powder metallurgy. The composite is found to be composed of two ultrafine-grained (UFG) phases including a body-centered cubic (bcc) solid-solution phase and a face-centered cubic (fcc) ceramic reinforcement phase (Ti, Nb)C. The as-sintered composite shows a uniform and UFG microstructure where two phases are interconnected. Due to this unique microstructure, the Ti40Nb15Mo30(NbC)15 composite displays superb specific yield strengths among surveyed RHEAs, complex concentrated alloys, and metal-matrix composites from 800°C (243 MPa·g-1·cm3) to 1000°C (127 MPa·g-1·cm3). The outstanding high-temperature compressive strength was found to be associated with high resistance to dislocation motion and strong dislocation interactions in both the bcc and fcc phases. The phase interface after hot compression remained semi-coherent, vindicating its high stability. The high-density of stable phase interfaces not only retards the dislocation motion due to the large image force near the phase boundary but also induces a high value of activation energy for diffusion. The high activation energy can further achieve significant microstructure stability even after a long-term annealing (36 h) at 1000°C. This work provides new perspectives for the design and application of light and ultrastrong refractory complex concentrated alloys (RCCAs) by comparison to the insufficient strength of many traditional and light RCCAs.

Solution treatment-induced re-precipitation behavior in a selective laser melted Ti-12Mo-6Zr-2Fe alloy

Solution treatment (ST) can be considered as an effective method with multifunctional effects on the material properties. However, re-precipitation effect of ST on the selective laser melted (SLM) Ti-12Mo-6Zr-2Fe (TMZF) alloy have not been revealed. In this work, microstructural evolution and mechanical properties of SLM TMZF before and after a ST were studied. Triggered by the element diffusion-driven factor, as-fabricated (AF) samples with full β-Ti phase transformed into ST samples with α″-Ti phase and β-Ti phase during ST. Moreover, re-precipitation effect caused by α″-Ti phase significantly improved the mechanical properties of SLM TMZF.

Study of Synthesis Processes of Superconducting (?) MAX Phase Ti2InN

Study of Synthesis Processes of Superconducting (?) MAX Phase Ti₂InN

Magnetic properties and microstructure of Ce and Zr synergetic stabilizing Ti-lean SmFe12-based strip-casting flakes

Recently ThMn12-type samarium iron alloys have been promising materials for permanent magnets. Due to the high abundance and low cost, Ce as a possible stabilizer can be introduced into ThMn12-type alloys. The effect of Ce doping on the magnetic moment and phase stability in Ti-lean (Ce,Sm,Zr)(Fe,Co,Ti)12 compounds were predicted by the first-principles calculations. The CexSm0.8-xZr0.2(Fe0.8Co0.2)11.5Ti0.5 (x = 0–0.8) alloys with ThMn12 structure were produced by strip-casting into flakes by a wheel speed of 1.5 m/s and annealed at 1000 °C for 24 h. The Ce0.8Zr0.2(Fe0.8Co0.2)11.5Ti0.5 annealed flake shows a high saturation magnetization value of 13.6 kGs at room temperature. With the increase of Ce substitution in the annealed flakes, the content of α-(Fe,Co,Ti) phase decreases and the saturation magnetization increases. The 1:12 phase and the 1:9 phase have an orientation relationship that can be expressed as [0 0 –1]1:12//[100]1:9 and (020)1:12//(010)1:9. Besides, annealing process promotes the formation of 1:12 phase transformed from 1:9 phase. Coercivity is expected to be improved by obtaining uniform microstructure and suppressing the formation of soft α-(Fe,Co,Ti) phase in the ThMn12-based alloys.

Magnetron-Deposited FeTiB Films: From Structural Metastability to the Specific Magnetic State

Results of XRD and TEM studies of a metastable phase state in Fe73Ti5B19O3 and Fe55Ti16B27O2 films, which is formed upon magnetron deposition under preset conditions, and of the evolution of the state in the course of subsequent annealing at 500 °C for 1, 5, and 9 h and experimental data on the magnetic microstructure and magnetic properties are reported. The annealed films were found to be characterized by a nanocrystalline structure, which is represented by two crystalline phases, namely, the ferromagnetic solid solution αFe(Ti), and nonferromagnetic boride FenB. The Ti content in the films determines the grain size of the αFe(Ti) phase, whereas the content of B localized within the grain boundaries determines the ratio of the volume fractions of amorphous and nanocrystalline phases in the structure. In contrast to the ferromagnetic Fe73Ti5B19O3 films, the Fe55Ti16B27O2 films are superparamagnets both in the deposited state and after annealing at 500 °C for 1 and 5 h because of the higher volume fraction of the amorphous phase in the structure. The 9 h annealing of the Fe55Ti16B27O2 films transfers them into the ferromagnets owing to the development of the amorphous phase crystallization, increase in the content of nanocrystalline ferromagnetic phase αFe(Ti) grains, and realization of exchange interaction between them.

Synthesis of (Ti, W, Mo) CN based cermets with different carbides configurations for demanding applications: Study of the crystal structure, microstructure, and mechanical properties

In this study, based on different element configurations within constant atomic ratio of elements, (Ti0.93W0.07Mo0.07)C–20%Ni and (Ti0.93W0.07Mo0.07)CN0.3-20%Ni derived cermets have been synthesized. The basis for the difference in the production route was whether the carbides were formed by carbothermic reaction from the metal oxide together or separately, or in the case of Mo2C, the carbide is added to the mixture together with the binder after reduction and just before consolidation. Another basis for the difference was whether the cermet was a carbide or a carbonitride. To investigate the influence of the different production routes, the crystal structure, microstructure, and mechanical properties of the cermets produced were examined using XRD, FESEM, STEM, and Vickers indentation. The XRD spectra of all the cermets were found to be very similar to those of TiC-based cermets, indicating that the additive carbides in the TiC or Ti(CN) phases of the cermets dissolve perfectly during the high vacuum sintering process at 1510 °C. The highest toughness (14.65 MPa m1/2) was obtained in (Ti0.93W0.07) C–8%Mo2C–20Ni cermets with a core-rim structure. In addition, the use of nitrogen leads to a dramatic reduction in particle size. The use of molybdenum and tungsten in the form of separate carbides had little effect on limiting the expansion of crystal size and grain size compared to the scenario where the dissolution of these elements took place within the primary core-rim structure. However, in terms of hardness and toughness, it was found that, in addition to grain size, the route taken in the addition of molybdenum and tungsten was also important.