As-cast Counterpart Research Articles

Microstructures of Directionally Solidified Nb15Ti55Fe30 Alloy and Its Hydrogen Permeation Properties in the Presence of H2S

Currently, the main limitations of Pd-coated Nb-TiFe dual-phase alloys include insufficient hydrogen permeability, susceptibility to hydrogen embrittlement (HE), and poor tolerance of H2S poisoning. To address these issues, this study proposes a series of improvements. First, a novel Nb15Ti55Fe30 alloy composed of a well-aligned Nb-TiFe eutectic was successfully prepared using directional solidification (DS) technology. After deposition with a Pd catalytic layer, this alloy exhibits high hydrogen permeability of 3.71 × 10−8 mol H2 m−1 s−1 Pa−1/2 at 673 K, which is 1.4 times greater than that of the as-cast counterpart. Second, to improve the H2S corrosion resistance, a new Pd88Au12 catalytic layer was deposited on the surface using a multi-target magnetic control sputtering system. Upon testing in a 100 ppm H2/H2S mixture, this membrane exhibited better resistance to bulk sulfidation and a higher permeance recovery (ca. 58%) compared to pure Pd-coated membrane. This improvement is primarily due to the lower adsorption energies of the former with H2S, which hinders the formation of bulk Pd4S. Finally, the composition region of the Pd-Au catalytic membrane with high comprehensive performance was determined for the first time, revealing that optimal performance occurs at around 12–18 at.% Au. This finding explains how this composition maintains a balance between high H2 permeability and excellent sulfur resistance. The significance of this study lies in its practical solutions for simultaneously improving hydrogen permeability and resistance to H2S poisoning in Nb-based composite membranes.

Additive manufacturing nickel-aluminum bronze alloy via wire-fed electron beam directed energy deposition: Enhanced mechanical properties and corrosion resistance compared to as-cast counterpart

In the present work, a wall-structured nickel-aluminum bronze (NAB) alloy was fabricated via electron beam directed energy deposition (EB-DED) additive manufacturing with a single-pass multi-layer deposition strategy. A comprehensive comparative analysis of microstructure, mechanical properties, and corrosion resistance was conducted against a conventionally cast NAB alloy. The inherent rapid solidification and cyclic thermal processing of the EB-DED technique profoundly influenced the microstructural evolution of the NAB alloy. The as-deposited NAB alloy exhibited a fine-grained microstructure, devoid of the martensitic β′ phase, accompanied by the spheroidization of partial κIII precipitates, and a homogeneous distribution of alloying elements. These distinctive microstructural attributes synergistically enhanced the strength, hardness, and toughness of the NAB alloy, conferring superior mechanical properties compared to its cast counterpart. Furthermore, the as-deposited alloy demonstrated remarkable corrosion resistance in a 3.5 wt% NaCl solution, significantly outperforming the cast alloy. The underlying mechanisms governing the structure-property relationships were elucidated. This comprehensive investigation provided insights into the unique characteristics and potential applications of EB-DED fabricated NAB alloys, positioning them as promising candidates for high-performance components subjected to severe mechanical and corrosive service conditions.

Cavitation erosion-corrosion properties of as-cast TC4 and LPBF TC4 in 0.6 mol/L NaCl solution: A comparison investigation

In this work study, a comparative analysis was undertaken to investigate investigation into the cavitation erosion (CE) and corrosion behavior of laser powder bed fusion (LPBF) TC4 and as-cast TC4 in 0.6 mol/L NaCl solution. Relevant results indicated that LPBF TC4 revealed a rectangular checkerboard-like pattern with a more refined grain size compared to as-cast TC4. Meanwhile, LPBF TC4 surpassed its as-cast counterpart in CE resistance, demonstrating approximately 2.25 times lower cumulative mass loss after 8 h CE. The corrosion potential under alternating CE and quiescence conditions demonstrated that both LPBF TC4 and as-cast TC4 underwent a rapid potential decrease at the initial stages of CE, while a consistent negative shift in corrosion potential was observed with the continuously increasing CE time, indicative of a gradual decline in repassivation ability. The initial surge in corrosion potential during the early CE stages was primarily attributed to accelerated oxygen transfer. As CE progressed, the significant reduction in corrosion potential for both LPBF TC4 and as-cast TC4 was attributed to the breakdown of the passive film. The refined and uniform microstructure in LPBF TC4 effectively suppresses both crack formation and propagation, underscoring the potential of LPBF technology in enhancing the CE resistance of titanium alloys. This work can provide important insights into developing high-quality, reliable, and sustainable CE-resistant materials via LPBF technology.

SolidStir technology: A novel solid-state integrated manufacturing process for structural fabrication

Present study introduces SolidStir® as an integrated solid-state manufacturing technique for extrusion of rods, wires, tubes, and metal-matrix composites with an additional additive manufacturing (AM) capability. The technology has the advantage of using plug-and-play components to enable multiple end products. The extrudates benefit from an equiaxed, and refined microstructure (∼15 µm). AM of Al-15Ce-3Zr alloy showed severe particle breakdown and exhibited better mechanical properties (∼27 % and ∼900 % increase in strength and ductility) compared to the as-cast counterpart. Leveraging the advantages of solid-state manufacturing, this work establishes SolidStir® as a unique solution for modular manufacturing far and beyond the frontiers of earth.

A Microstructural Study of Cu-10Al-7Ag Shape Memory Alloy in As-Cast and Quenched Conditions

Shape memory alloys (SMAs) represent an exceptional class of smart materials as they are able to recover their shape after mechanical deformation, making them suitable for use in actuators, sensors and smart devices. These unique properties are due to the thermoelastic martensitic transformation that can occur during both thermal and mechanical deformation. Cu-based SMAs, especially those incorporating Al and Ag, are attracting much attention due to their facile production and cost-effectiveness. Among them, Cu-Al-Ag SMAs stand out due to their notably high temperature range for martensitic transformation. In this study, a Cu-based SMA with a new ternary composition of Cu-10Al-7Ag wt.% was prepared by arc melting and the samples cut from this casting alloy were quenched in water. Subsequently, the phase composition and the development of the microstructure were investigated. In addition, the morphology of the martensite was studied using advanced techniques such as electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The analyzes confirmed the presence of martensitic structures in both samples; mainly 18R (β1′) martensite was present but a small volume fraction of (γ1′) martensite also was noticed in the as-quenched sample. The observation of fine, twinned martensite plates in the SMA alloy with symmetrically occurring basal plane traces between the twin variants underlines the inherent correlation between microstructural symmetry and the properties of the material and provides valuable insights into its behavior. The hardness of the quenched sample was found to be lower than the as-cast counterpart, which can be linked to the solutioning of Ag particles during the heat treatment.

Endowing low fatigue for elastocaloric effect by refined hierarchical microcomposite in additive manufactured NiTiCuCo alloy

NiTiCu-based shape memory alloys have been considered as ideal materials for solid-state refrigeration due to their superb cycling stability for elastocaloric effect. However, the embrittlement and deterioration caused by secondary phase and coarse grains restrict their applications, and it is still challenging since the geometric components are required. Here, bulk NiTiCuCo parts with excellent forming quality were fabricated by laser powder bed fusion (LPBF) technique. The as-fabricated alloy exhibits refined three-phases hierarchical microcomposite formed based on the rapid cooling mode of LPBF, composed of intricate dendritic Ti2Ni–NiTi composite and nano Ti2Cu embedded inside the NiTi-matrix. This configuration endows far superior elastocaloric stability compared to the as-cast counterpart. The low fatigue stems from the strong elastic coupling between the interphases with reversible martensite transformation, revealed by in-situ synchrotron high-energy x-ray diffraction. The fabrication of NiTiCuCo alloy via LPBF fills the bill of complex geometric structures for elastocaloric NiTiCu alloys. The understanding of interphase micro-coupling could provide the guide for designing LPBF fabricated shape memory-based composites, enabling their applications for special demands on other functionalities.

Enhancing strength and ductility in high Nb-containing TiAl alloy additively manufactured via directed energy deposition

Intermetallic TiAl alloys have found applications in the aerospace and automotive fields. Nevertheless, to satisfy the increasingly complex environmental requirements, these lightweight alloys must be improved particularly in strength and ductility. Additive manufacturing (AM) exhibits a rapid solidification rate and may strengthen intermetallic TiAl alloys. In this study, an additively manufactured (AMed) Ti-48Al-8 Nb alloy with fine formability was successfully fabricated by optimizing the power used during directed energy deposition. The preferential crystal plane for the obtained alloy is {111}γ due to its lowest surface energy, and the presence of the thermal gradient during the AM process results in the alloy growing along the building direction. The TiAl alloy AMed at 500 W delivers an excellent tensile strength of 880 MPa that is 1.71 times higher than that of its as-cast counterpart, as well as elongation of 0.7% at room temperature. The superior properties of this alloy are due to the formation of numerous deformation twins during tensile deformation at room temperature that enables twin intersections to produce high-density nano-twins while contributing to stress release. Moreover, the AMed TiAl alloy exhibits outstanding high-temperature strength retention performance.

Sub-Rapid-Solidification Dominated Microstructure Modification and Strength Increment for Wire-Arc Directed Energy Deposited Al-Ce-Mg Alloys

Conventional cast Al-Ce alloys are challenged by the increasing demand for improved mechanical properties. To address this issue, in this study, wire-arc directed energy deposition (WA-DED) is employed for the fabrication of Al-15Ce-3Mg (wt%) alloy components. We aimed to tune the microstructure and mechanical properties via the inherent sub-rapid-solidification effect of WA-DED. In addition to significant microstructure refinement, a decrease in arc heat input leads to a larger cooling rate, up to 346 °C/s, and triggers the transition from hypereutectic to near-eutectic α-Al/Al11Ce3 microstructures with the suppression of primary Al11Ce3 intermetallics. Such microstructural modification improves the mechanical properties, resulting in higher yield and ultimate tensile strengths than those of the as-cast counterpart alloy. The fracture process involves the formation of dimples around Al11Ce3, cracking of large Al11Ce3 particles, and growth, merging, and fracture of pores. The strength increment is mainly contributed by particle-size strengthening mediated by microstructure refinement as well as the targeted formation of near-eutectic α-Al/Al11Ce3 microstructures.

Advanced cavitation erosion-corrosion resistance of nickel-aluminum bronze prepared by directed energy deposition

The mechanical properties and cavitation erosion-corrosion behavior of directed energy deposition (DED) and as-cast nickel-aluminum bronze (NAB) alloys in 3.5 wt% NaCl solution were investigated. The DED-produced NAB alloy showed a finer microstructure, and the content of κ phases significantly decreased, improving yield strength (increased by 27.76%) and elongation (increased by 54.89%) of NAB alloy. The DED-produced NAB exhibited a more uniform microstructure, fewer high-angle grain boundaries (HAGBs), and twin boundaries (∑3), resulting in a weakened synergistic effect between corrosion and mechanical attack. Compared with the as-cast counterpart, the mass loss rate of DED-produced NAB decreased by 74.77%.

Additive manufacturing of defect-free TiZrNbTa refractory high-entropy alloy with enhanced elastic isotropy via in-situ alloying of elemental powders

Laser powder-bed fusion (L-PBF) additive manufacturing presents ample opportunities to produce net-shape parts. The complex laser-powder interactions result in high cooling rates that often lead to unique microstructures and excellent mechanical properties. Refractory high-entropy alloys show great potential for high-temperature applications but are notoriously difficult to process by additive processes due to their sensitivity to cracking and defects, such as un-melted powders and keyholes. Here, we present a method based on a normalized model-based processing diagram to achieve a nearly defect-free TiZrNbTa alloy via in-situ alloying of elemental powders during L-PBF. Compared to its as-cast counterpart, the as-printed TiZrNbTa exhibits comparable mechanical properties but with enhanced elastic isotropy. This method has good potential for other refractory alloy systems based on in-situ alloying of elemental powders, thereby creating new opportunities to rapidly expand the collection of processable refractory materials via L-PBF.

Microstructural effects on the ambient temperature indentation creep behavior of metastable β Ti-5Al-5V-5Mo-3Cr alloy

Ti-5553 alloy is considered as a potential candidate for heavy structural components such as landing gears in aerospace industries, that operate particularly at room temperature. For achieving the targeted performance, microstructural modification and corresponding improvement in mechanical properties, particularly room temperature creep behavior of Ti-5553 alloy is of significant concern. In this regard, an optimized thermomechanical processing (TMP) schedule is employed to tailor the microstructure of as-cast Ti-5553 alloy. Typical bimodal microstructure containing both α and β phases is noted to evolve upon TMPing, as compared to its as-cast counterpart, having sole β phase. The size and volume fraction of αp are noted to be 0.85 ± 0.39 µm and 11.7 ± 0.5%, respectively. Such pronounced variation in the microstructural features is expected to alter the localized mechanical properties significantly. To assess that, room temperature small-scale creep behavior of as-cast and TMPed Ti-5553 alloys is investigated using nanoindentation technique. The effect of maximum load on different creep parameters are analyzed and correlated with the corresponding microstructures. It is noted that at any particular applied load level, creep deformation of TMPed Ti-5553 alloy is ∼ 20–64% lower than that for the as-cast one. This is reflected in significant reduction in the minimum creep strain rate from 10−4 s−1 for as-cast to 10−5 s−1 for TMPed Ti-5553 alloy. Dislocation creep mechanism is found to be active for both the alloys since creep exponent for both the as-cast and TMPed Ti-5553 alloys exceed the value of 2. Discontinuous semi-circular micro-shear bands are noted to form around the indents for the as-cast Ti5553 alloy. The kernel average misorientation map for this alloy reveals a lower degree of misorientation and a more homogeneous distribution of plastic strain. In contrary, the TMPed Ti-5553 alloy exhibits higher misorientation around the indent impression, thereby indicating towards the restriction of dislocation movement against α/β laths and hence positively influencing the creep behavior. Overall, the study highlights the important role of TMP in enhancing the creep resistance of Ti-5553 alloy for industrial applications.

Strength-ductility synergy of an additively manufactured metastable high-entropy alloy achieved by transformation-induced plasticity strengthening

This study investigated the microstructures and mechanical properties of a metastable high-entropy alloy (HEA) Fe34Co34Cr20Mn6Ni6 produced by laser powder bed fusion (LPBF) and compared them with those of an as-cast one. The LPBF-processed HEA exhibited a face-centered cubic (FCC) structure due to the high cooling rate of the laser-induced melt pools. In contrast, the as-cast HEA featured a mass of hexagonal close-packed (HCP) phase within the FCC matrix due to the elemental segregation resulting from low cooling rates. The LPBF-processed HEA exhibited superior strength-ductility synergy when compared to its as-cast counterpart. The yield strength, ultimate strength, and plasticity of the LPBF-processed HEA were 305 MPa, 808 MPa, and 18.9 %, respectively, which were much higher than those of the as-cast HEA (171 MPa, 463 MPa, and 7.3 %). This strength-ductility synergy was attributed to the in-situ formation of a fine HCP phase through the stress-induced phase transformation (TRIP) effect. The fine HCP phase provided abundant FCC/HCP interfaces, thus enhancing strong back stress hardening and facilitating the deformation uniformity. In contrast, the as-cast HEA displayed coarse and straight FCC/HCP interfaces that hindered back stress hardening. Moreover, the interaction between the pre-existing HCP phase and the stress-induced HCP phase in the as-cast HEA tended to cause stress concentration and subsequent crack initiation, leading to reduced ductility in the as-cast HEA. These findings are expected to provide valuable insights for a better understanding of additively manufactured TRIP-assisted HEAs.

Developing a novel high-strength Mg-Gd-Y-Zn-Mn alloy for laser powder bed fusion additive manufacturing process

Laser powder bed fusion (LPBF) of Mg alloys mainly focuses on the traditional commercial casting Mg alloys such as AZ91D, ZK60 and WE43, which usually display relatively low tensile strengths. Herein we developed a novel high-strength Mg-12Gd-2Y-1Zn-0.5Mn (wt.%, GWZ1221M) alloy for the LPBF additive manufacturing process, and the evolution of microstructure and mechanical properties from the as-built state to LPBF-T4 and LPBF-T6 states was systematically investigated. The as-built GWZ1221M alloy exhibited fine equiaxed grains with an average grain size of only 4.3 ± 2.2 μm, while the as-cast alloy displayed typical coarse dendrite grains (178.2 ± 73.6 μm). Thus, the as-built alloy showed significantly higher tensile strengths than the as-cast counterpart, and its yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) were 315 ± 8 MPa, 340 ± 7 MPa and 2.7 ± 0.5 % respectively. Solution treatment transformed hard and brittle β-(Mg,Zn)3(Gd,Y) phase into basal X phase and lamellar long period stacking ordered (LPSO) with better plastic deformability, leading to the improvement of EL. Then peak-aging heat treatment introduced numerous nano-sized prismatic β′ precipitates inside grains, resulting in the enhancement of YS. Finally, the LPBF-T6 alloy achieved appreciably high strength with YS, UTS and EL of 320 ± 3 MPa, 395 ± 4 MPa and 2.1 ± 0.4 % respectively. Both as-built and LPBF-T6 GWZ1221M alloys showed remarkably higher tensile strengths than the as-cast counterparts and as-built commercial Mg alloys, highlighting the great potential of high-strength as-built Mg-Gd based alloys for structural applications.

X-ray line profile analysis study on the evolution of the microstructure in additively manufactured 316L steel during severe plastic deformation

316L stainless steel was manufactured by additive manufacturing (AM), and then, the samples were severely deformed by the high-pressure torsion (HPT) technique. The evolution of the microstructure was monitored by X-ray line profile analysis. This method gives the crystallite size and the density of lattice defects, such as dislocations and twin faults. The AM-processing of the HPT disks was performed in two different modes: the laser beam was parallel or orthogonal to the normal direction of the disks. The subsequent HPT deformation was carried out for ½, 1, 5 and 10 turns. The microstructure and hardness evolution during HPT were similar regardless of the laser beam direction. For both sample series, the minimum achievable crystallite size was about 30 nm, while the dislocation density and the twin fault probability got saturated at the values of 300–350 × 1014 m−2 and 3.5–4%, respectively. The microstructure evolution during HPT of the AM-prepared 316L steel was compared with the HPT-induced changes in an as-cast counterpart. It was found that while the AM-prepared 316L steel remained a single-phase face-centered cubic γ-structure during HPT, in the as-cast samples a body-centered cubic (bcc) martensitic α-phase became the main phase with increasing the imposed strain of HPT due to the lower Ni content. In the saturation state achieved by HPT the initially as-cast 316L steel had a considerably higher hardness (about 6000 MPa) than that for the AM-prepared samples (~ 5000 MPa) due to the large fraction of the hard bcc phase formed during HPT.

Synchronous improvement in mechanical properties and corrosion resistance of Mg-Gd-Ag-Zr alloy through nanoprecipitates

It is still challenging to synchronously improve mechanical properties and corrosion resistance through one strategy during developing Mg alloys. Introducing high-density precipitates is an effective and popular approach to strengthen Mg alloys, while these precipitates generally degrade the corrosion resistance. In this paper, the nanoprecipitates are developed in Mg-13.4Gd-2.2Ag-0.4Zr wt.% cast alloy through the solution and aging treatment for evading this dilemma. Compared with its as-cast counterpart, the peak-aged alloy with high-density nanoprecipitates exhibits enhanced strength, comparable ductility, and improved corrosion resistance. The nanoprecipitates in the peak-aged alloy are composed of β nanoparticles at grain boundaries, and intragranular γ′′ and β′ nanoplates. These nanoprecipitates are contributed to the improved strength through the Orowan mechanism. The β nanoparticles induce weak galvanic corrosion, and the γ′′ nanoplates have not induced visible galvanic corrosion, thus contributing to the enhanced corrosion resistance of the peak-aged alloy. This result suggests that developing nanoprecipitate is a feasible route to collaboratively optimize the mechanical and corrosion properties of the Mg alloys.

Structural and stress state dependence of small-scale deformation in bulk metallic glass

Bulk Metallic Glasses (BMGs) are attractive for myriad structural applications at multiple length scales (nano-micro-macro) but show limited bulk plasticity due to the tendency for shear localization. However, there is limited understanding of the effect of structural state and stress state on the small-scale deformation behavior of BMGs. Here, the micro-scale deformation behavior of a model Ni-based BMG was studied in as-cast and corresponding relaxed state under multiaxial nano-indentation, uniaxial micro-pillar compression, and micro-cantilever beam bending. The relaxed BMG showed 6 % higher hardness, 22 % higher yield strength, and 26 % higher bending strength compared to its as-cast counterpart. The increase in hardness, yield strength, and bending strength for the relaxed alloy compared to its as-cast counterpart demonstrates the relation of intrinsic free volume present in a BMG to its resistance for initiation of plastic events at this scale. Both the as-cast and corresponding relaxed samples showed stable notch opening and blunting during micro-cantilever bending tests rather than unstable crack propagation. However, pronounced notch weakening was observed for both the structural states, with the bending strength lower by ∼ 25 % for the notched samples compared to the un-notched samples. This work may stimulate further investigations into the deformation behavior of BMGs in response to complex stress states pertinent to real-world structural applications at small scale.

Unexpected creep behavior in a rejuvenated metallic glass

Rejuvenation, bringing metallic glasses (MGs) to the younger and higher energy states, provides an alternative avenue to explore the interplay between the property and microstructures of MGs. In this study, the creep behavior of the Zr69.5Cu12Ni11Al7.5 MGs was experimentally examined by controlling the energy state in terms of structural rejuvenation and thermal annealing. It is found that compared to the as-cast counterpart, the annealed MG at a lower energy state exhibits a higher hardness, a smaller displacement, and a lower creep rate due to the decreased free volume and the inhibited activation of the shear transformation zone. Conversely, the rejuvenated MG at a high energy state displays lower hardness and increased free volume content, yet it demonstrates superior creep resistance compared to its as-cast counterpart, which deviates from conventional understanding. This unexpected phenomenon occurs as the initial high-content free volume annihilates during creep, and strain hardening takes precedence over strain softening as the prevailing process during creep deformation, leading to a superior creep performance in extremely rejuvenated MGs.

Grain refinement and improved mechanical properties of Mg-4Zn-0.5Ca-0.5RE magnesium alloy by thermomechanical processing

The high strength Mg-4Zn-0.5Ca-0.5RE magnesium alloy was subjected to different hot deformation processes of extrusion, forging, and their combination for grain refinement and improvement of mechanical performance. A fine dynamically recrystallized (DRX) microstructure was obtained by the extrusion process accompanied with the fragmentation and dispersion of the eutectics toward eliminating their deleterious effects, which led to a major improvement in the mechanical properties compared with the as-cast counterpart. However, the forging process led to the development of a partially recrystallized microstructure, indicating the necessity for the application of high strains. On the other hand, detailed electron backscatter diffraction (EBSD) analysis revealed that the combination of extrusion and forging is effective for more intense grain refinement (compared to the extrusion process), leading to the improved yield and ultimate tensile strength while maintaining high ductility (total elongation). A threshold value of grain orientation spread (GOS) was proposed for separating the DRX grains from the deformed ones (below 2° for the DRX grains). Moreover, the DRX grain size was correlated with the Zener-Hollomon parameter. These findings can shed light on the industrial application of this wrought Mg alloy.

V0.5Nb0.5ZrTi refractory high-entropy alloy fabricated by laser addictive manufacturing using elemental powders

In this work, a V0.5Nb0.5ZrTi refractory high-entropy alloy is successfully fabricated by the selective laser melting (SLM) method using elemental powders as precursors. A crack-free SLM-prepared (SLMed) sample with a nearly single BCC structure is acquired with a volume energy density (VED) of 333 J/mm3. However, when the VED is lower or higher than 333 J/mm3, microcracks are generated in the SLMed samples. The finite element method simulation reveals that there are two mechanisms for generation of cracks. When VED < 333 J/mm3, Zr particles are not completely melted. Cracks are formed around the Zr particles due to the crystalline structure and coefficient of thermal expansion mismatches between the unmelted Zr particles and the alloyed BCC matrix. When VED > 333 J/mm3, cracks are formed due to thermal stress induced by the large temperature gradient during the SLM process. In addition, the SLMed crack-free sample exhibits much better mechanical properties than the as-cast counterpart. The current study provides a reference for the application of SLM technology to prepare refractory high-entropy alloys with excellent mechanical properties using elemental powders as the precursor.

Improved mechanical properties of a Ti-48Al alloy processed by mechanical alloying and spark plasma sintering

Bulk Ti-48Al alloy samples were prepared by the high energy ball milling (HBM) of elemental powders, followed by spark plasma sintering (SPS) of the HBM processed powders. The microstructure, phase evolution and mechanical properties of the bulk alloy were studied. The resulting TiAl + Ti3Al two phase alloy possessed an equiaxed fine grain structure, unlike the usual lamellar structure produced by arc melting. The process parameters of HBM and SPS, e.g., milling speed, milling time and sintering temperature were used to tune the phase fraction, microstructure, and grain size. A very high nanohardness of up to ∼12 GPa was obtained, ∼2.4 times higher than the corresponding value of the as-cast counterpart. The combined influence of powder size reduction during HBM, high Ti3Al phase fraction and microstructural development during SPS resulted in higher hardness, wear resistance and yield pressure. Thus, a HBM+SPS processing approach is a promising processing route for the manufacture of high hardness bulk TiAl alloys.