TiAl Research Articles

Microstructure and mechanical properties of additively manufactured γ-TiAl with dual microstructure

The latest research on electron beam powder bed fusion (PBF-EB), additive manufacturing (AM) process, reveals the possibility of establishing a dual microstructure and differing mechanical properties inside a complex-shaped component made of titanium aluminides (TiAl). The functionally graded material (FGM) parts are processed with two different, well-adjusted AM process parameter sets leading to a significant change in localized aluminum (Al) loss via evaporation during PBF-EB. By heat treatment, the as-built microstructure, containing two different levels of Al, is transformed into customized microstructures: fully lamellar (FL) and nearly lamellar (NL + γ). This study aims to determine the microstructural and mechanical characteristics of PBF-EB processed 4th generation TiAl alloy TNM. Tensile and creep tests are performed for single (FL or NL + γ) and dual microstructure specimens with two orientations. The element distribution of aluminum is determined, the microstructures are characterized, and the fracture-inducing defects are identified. The presented new FGM processing route is a groundbreaking benefit from the PBF-EB process and is necessary for superior mechanical performance. The stress-strain and the creep properties of the dual microstructure specimens are situated between the single microstructure specimens. The mechanical characterization shows that the interface between FL and NL + γ does not cause any weakening of the specimens. The failure always takes place in the weaker microstructure (tensile: FL; creep: NL + γ). For the first time, AM components such as TiAl turbine blades can consist of creep-resistant airfoil sections and high-strength root sections taking advantage of new microstructural FGM design possibilities.

Tailoring role of Al and Ti particles in the microstructure and property of electrodeposited Ni matrix nanocomposite coatings

Ni–Al–Ti nanocomposite coatings were synthesized by electrodeposition. The tailoring role of Al and Ti particles in the co-deposition behaviors of nanocomposite coatings was comprehensively investigated by analyzing the time-dependent current density and electric field near the co-deposited particles. The results showed that the Al and Ti particles caused different co-deposition behaviors of Ni deposits, consequently bringing in the gradual increase in the surface dendritic structure, the refinement of grain sizes, and the decrease in the [200] fiber texture of the nanocomposite coatings with the decrease in the Al/Ti weight ratio. COMSOL simulations verified the different co-deposition mechanisms of Ni grains near the two kinds of particles, which was vitally determined by the different conditions of current density and electric field near the particles. The micro-hardness results revealed that the decreased Al/Ti weight ratio led to enhanced micro-hardness of the nanocomposite coating; in addition, the maximum hardness of the nanocomposite coating was 604.3 HV0.2 for an Al/Ti weight ratio of 1:4. Thus, the time-dependent current density and electric field near co-deposited Al and Ti particles determined the microstructure and property of the Ni–Al–Ti nanocomposite coatings.

TEM Study of a Layered Composite Structure Produced by Ion-Plasma Treatment of Aluminum Coating on the Ti-6Al-4V Alloy

Using the methods of transmission electron microscopy and energy-dispersive spectroscopy, we study the microstructure and phase composition of the coating and modified intermetallic layers obtained in a Ti-6Al-4V alloy by the deposition of the Al coating and subsequent processing in low-pressure non-self-sustained arc discharge plasma (CIPT—complex ion-plasma treatment). The deposition of the aluminum coating on the Ti-6Al-4V alloy is accompanied by the formation of a layered and a gradient microstructure: nanocrystalline near the “coating/substrate” interface and ultrafine-grained in the outer part of the aluminum coating, with α-stabilized region of ≈5 µm thick in the surface layer in base titanium alloy. After the CIPT, the coating and the surface of the base titanium alloy have a layered morphology: each of the layers possesses different grain structure and composition. In the direction from the outer surface of the specimen to the base material, the following phase sequence has been confirmed by diffraction and elemental analysis: TiAl3 → TiAl3 + nc-(Al(Ti) + α-Ti) → nc-(Al(Ti) + α-Ti) → TiAl3 → TiAl3 + TiAl → TiAl → Ti3Al → α-Ti alloy → (α + β)-Ti alloy. The nanocrystalline aluminum layer, which has been formed during the deposition of the aluminum coating, does not undergo phase transformation and recrystallization under the CIPT. Nanocrystalline structure can favor the interdiffusion of the elements between the coating and base material, and stimulate phase transformation in coarser grains situated under and over it.

Gamma-ray, fast neutron and ion shielding characteristics of low-density and high-entropy Mg–Al–Ti–V–Cr–Fe–Zr–Nb alloy systems using Phy-X/PSD and SRIM programs

This study aimed to assess the radiation shielding properties of ten low-density high-entropy alloys (LWHEAs) using Phy-X/PSD software to analyze various shielding parameters, such as attenuation coefficients (μm and μ), mean free path (λ), effective atomic number (Zeff), and removal cross-section (ΣR), in the energy range of ▪ to ▪. A comprehensive evaluation was performed to compare the attenuation outcomes provided by HEAs with a range of shielding materials documented in the literature. The study also calculated the build-up factors (BUFs) of the alloys by using the GP-fitting interpolation method. The stopping power of the alloys against H1/He+2 ions was analyzed using the SRIM Monte Carlo code, considering total stopping power (TSP) and projected range (PR). The results indicated that HEA8 (Al3.88Cr14.95Mo27.58Nb26.71Ti13.76Zr13.11) had the best performance in terms of shielding against γ-rays, fast neutrons, and H1/He+2 ions, as it achieved the highest values of parameters such as μm, μ, Zeff, and ΣR, along with the lowest values of HVL, TVL, λ, BUFs (▪▪), TSP, and PR. On the other hand, HEA10 (Mg10.77Al11.96Mn24.35Fe24.75Cu28.17) had the lowest BUFs in both lower (▪▪) and higher (▪▪) energy regions. The order of μm for the alloys was found to be HEA5<HEA6<HEA9<HEA7<HEA10<HEA4<HEA2<HEA3<HEA1<HEA8. The study concluded that LWHEAs possess superior radiation shielding properties compared to conventional materials, making them a promising new class of materials for radiation shielding applications.

Variant selection of orthorhombic phase precipitation and its effect on colony side plates formation in Ti–22Al–25Nb alloy

Heat treatments with controlled cooling rates have been used to investigate orthorhombic (O) phase precipitation and its variant selection (VS) in Ti–22Al–25Nb alloy, a latest Ti2AlNb-based intermetallic alloy with excellent comprehensive properties. This study uncovers the misorientation types of different O variants mainly belong to two types with a sharing angle of 90° and distinct rotated axis of <012> or <100>. A notable lamellar structure, colony side plates (CSPs), frequently develop on both sides of adjoining B2 grains, which always have a detrimental effect on the final properties. This structure significantly influenced by VS, variants having (001) planes that are paralleled to the common {110} plane of adjacent B2 grains are selected in colony plates on both sides. If the <111> axis of the two B2 grains coincidentally close as well, the colony plates may appear to penetrate the GB. Moreover, the CSPs structure could form on condition of much slow cooling rate after holding in rather high temperature. These findings could provide insights on how to control processing conditions and tailor the lamellar structure to obtain the desired properties.

Considering the Value of 3D Cultures for Enhancing the Understanding of Adhesion, Proliferation, and Osteogenesis on Titanium Dental Implants.

Individuals with pathologic conditions and restorative deficiencies might benefit from a combinatorial approach encompassing stem cells and dental implants; however, due to the various surface textures and coatings, the influence of titanium dental implants on cells exhibits extensive, wide variations. Three-dimensional (3D) cultures of stem cells on whole dental implants are superior in testing implant properties and were used to examine their capabilities thoroughly. The surface micro-topography of five titanium dental implants manufactured by sandblasting with titanium, aluminum, corundum, or laser sintered and laser machined was compared in this study. After characterization, including particle size distribution and roughness, the adhesion, proliferation, and viability of adipose-derived stem cells (ADSCs) cultured on the whole-body implants were tested at three time points (one to seven days). Finally, the capacity of the implant to induce ADSCs' spontaneous osteoblastic differentiation was examined at the same time points, assessing the gene expression of collagen type 1 (coll-I), osteonectin (osn), alkaline phosphatase (alp), and osteocalcin (osc). Laser-treated (Laser Mach and Laser Sint) implants exhibited the highest adhesion degree; however, limited proliferation was observed, except for Laser Sint implants, while viability differences were seen throughout the three time points, except for Ti Blast implants. Sandblasted surfaces (Al Blast, Cor Blast, and Ti Blast) outpaced the laser-treated ones, inducing higher amounts of coll-I, osn, and alp, but not osc. Among the sandblasted surfaces, Ti Blast showed moderate roughness and the highest superficial texture density, favoring the most significant spontaneous differentiation relative to all the other implant surfaces. The results indicate that 3D cultures of stem cells on whole-body titanium dental implants is a practical and physiologically appropriate way to test the biological characteristics of the implants, revealing peculiar differences in ADSCs' adhesion, proliferation, and activity toward osteogenic commitment in the absence of specific osteoinductive cues. In addition, the 3D method would allow researchers to test various implant surfaces more thoroughly. Integrating with preconditioned stem cells would inspire a more substantial combinatorial approach to promote a quicker recovery for patients with restorative impairments.

Role of alloy composition on micro-cracking mechanisms in additively manufactured Ni-based superalloys

Inherent micro-cracking mechanisms in two contrasting high-gamma-prime (high-γ’) Ni-based superalloys processed by laser powder bed fusion (LPBF) were investigated. RENÉ 65 (R65) has a 42% γ’ volume fraction including Al, Ti, and Nb, while RENÉ 108 (R108) has a higher γ’ volume fraction (63%) including Al, Ta, and lesser Ti. Quantitative analysis showed R108 exhibits 329% higher micro-cracking density than R65. All micro-cracks propagate along high angle boundaries (HABs) and exhibit interdendritic morphologies suggesting solidification cracking is the dominant micro-cracking mechanism. Moreover, secondary phases detrimental for solid-state cracking are not observed at the HABs. Atom probe tomography (APT) showed preferential segregation of Hf, Mo, C, B at the R108 HAB and Zr, Ti, Mo, C, B at the R65 HAB. The Kou solidification cracking criterion showed that Hf and Zr partitioning along the grain boundaries increases micro-cracking susceptibility. Gamma prime did not form during the LPBF process and titanium has a higher tendency than tantalum to partition in the last liquid to solidify.

Low-temperature plasma nitriding at 500°C on surface-nanocrystalline Ti–4Al–2V alloy

Both surface nanocrystallization and high temperature favor nitrogen diffusion during plasma nitriding, but the surface nanostructure may be destroyed by high temperature to lose its diffusion-enhancing effect. In this paper, the combined effect of surface nanocrystallization by shot peening (SP) and nitriding temperature on the plasma nitriding of Ti–4Al–2V titanium alloy was studied. The results show that the interaction of nanocrystallization and temperature on plasma nitriding balanced best at 500 °C of the Ti–4Al–2V sample shot peened at both 0.2 MPa-10 min and 0.6 MPa-10 min. At this temperature, the surface nanocrystalline had maintained its thermal stability to some extent and played the greatest role in promoting nitrogen diffusion by more grain boundaries and a thickest nitrided layer was obtained on the SPed sample. The SPed sample nitrided at 500 °C exhibited better corrosion resistance and interface adhesion than the coarse-grained sample due to its denser/thicker nitrided layer and the retained gradient structure. In addition, the effect of surface roughness under different SP pressures on the corrosion resistance and adhesion of the nitrided layer was also concerned. A small surface roughness obtained under a low SP pressure was beneficial to improve the corrosion resistance and reflect the true adhesion of the nitrided layer.

Influence of Silicon and Chromium on the Na2SO4-Induced Hot Corrosion Behavior of Titanium Alloys

Titanium alloys are widely used as construction materials in the aerospace and automotive industries. They have many advantages but also have limitations related to their susceptibility to high-temperature oxidation and hot corrosion. Many efforts to increase the lifetime of components made of titanium alloys have been reported in the literature; the most promising ones involve the deposition of coatings. The present paper is focused on the development of coatings containing chromium and silicon, and their further evaluation in hot corrosion tests. It was proved that the Cr-Si coatings were more effective than Si coatings alone in protecting the titanium alloys against Na2SO4-induced hot corrosion at 800 °C. The enhanced corrosion resistance was attributed to the preferential formation of a thick and continuous SiO2 layer on the surface and—in the case of titanium aluminide alloy—the growth of an Al2O3-rich inner layer of the scale, promoted by chromium.

On the stability of Ti(Mn,Al)2 C14 Laves phase in an intermetallic Ti–42Al–5Mn alloy

In order to facilitate a more widespread use of intermetallic γ-TiAl based alloys in the aircraft and automotive sector, recent research focuses on the development of low-cost titanium aluminides. The strong β-stabilizing effect as well as the increased ductility upon Mn addition renders this alloying element a promising candidate to fully or partially substitute other, more expensive, alloying elements such as Mo, Ta and Nb. Mn-containing γ-TiAl based alloys, however, are prone to the formation of the undesired, brittle Ti(Mn,Al)2 C14 Laves phase during long-term exposure at the targeted service temperatures, which can deteriorate the ductility at ambient temperatures. In this study, the transformation kinetics as well as the chemical and thermal existence range of the C14 Laves phase in the low-cost Ti–42Al–5Mn (at.%) alloy were investigated by complementary experimental and computational approaches. In situ and ex situ high-energy X-ray diffraction in combination with microstructural investigations were used to study the occurrence and transformation kinetics of possible Laves phase formation in the course of annealing treatments. The chemical stability range of the C14 Laves phase was addressed by chemical analysis in conjunction with complementary ab initio modeling. Using these combined approaches, the critical local Mn concentration of ∼16 at.% for Laves phase formation within lamellar α2 and ∼17 at.% within βo in the Ti–42Al–5Mn alloy was determined. These results should be critically considered for future design of advanced low-cost γ-TiAl based alloys.

Comparative study on the effect of test temperature on tensile and charpy impact properties of Ti–5Al–1V–1Sn–1Zr-0.8Mo alloy

Impact toughness is a critical indicator to prevent catastrophic failure, especially at low service temperature. At present, most strategies to strengthen and toughen Ti alloys are proposed under the quasi-static tensile deformation condition. In fact, whether these strategies can be directly extended to improve impact toughness is still controversial due to the high loading rate and the existing of pre-notch during Charpy impact deformation condition. In this work, we found that, even though the yield strength and elongation of Ti–5Al–1V–1Sn–1Zr-0.8Mo alloy increase simultaneously with the decrease of test temperature under tensile deformation condition, the impact toughness still decreases gradually with the decreasing of deformation temperature under Charpy impact deformation condition. This phenomenon indicates that the successful strengthening and toughening strategies under quasi-static tensile deformation may fail under impact deformation. Finally, the reasons behind this phenomenon are explained based on the comparison of surface deformation morphologies under different deformation conditions, and the corresponding deformation mechanisms are established.

Effect of Scan Speed on Microstructure and Tensile Properties of Ti–48Al–2Cr–2Nb Alloys Fabricated via Additive Manufacturing

The morphology of microstructure and tensile properties of Ti–48Al–2Cr–2Nb (at%) alloy rods fabricated by the electron beam powder bed fusion (EB-PBF) process were investigated with a particular focus on the influence of scan speed of the electron beam. Homogeneous near lamellar structure composed of the α2 and γ phases can be obtained in the rod fabricated under the slowest scan speed. The fine lamellar spacing which contributes to the high strength of the alloy is derived from the fast-cooling rate of EB-PBF. On the contrary, a layered microstructure comprising a duplex-like region and an equiaxed γ grain layer (γ band) perpendicular to the building direction is obtained when increasing scan speeds. We observed for the first time that an increase in the scan speed results in a narrow width of the γ band. We also found that these microstructural changes have a significant influence on the mechanical properties of the rods. The near lamellar structure exhibits higher strength compared to the layered microstructure. Whereas, the rods with the layered microstructure show large ductility at room temperature. The elongation of each rod strongly depends on the width of the γ band owing to the preferential deformation of the γ band.

Повзучість малопластичних жароміцних матеріалів при вигині…

Express method of testing the initial creep stagiess of low-plastic heat-resistant materials that work in extreme conditions using the bending scheme proposed and developed. The features of stress and deformation calculation are analyzed. The limitations of using the elastic approximation are outlined: the degree of plastic deformation of the sample should not exceed 1—1,5%. The deflection should not exceed 10% of the distance between the supports, the height should not be greater than 1/10 of the distance between the supports. Under these conditions, the first and second stages are well distinguished on the creep curves. This makes it possible to analyze the influence of phase and structural changes on the mechanisms of creep at each stage, and the conditions for the transition to stationary creep. The results of model experiments performed on TNM titanium aluminide alloys and Fe3Al powder alloy samples indicate the expediency of using the three-point bending scheme for researching the initial stagiess of creep of heat-resistant materials. Experimentally determined values of the deformation rate vary in the range έ ~ 10-5—10-8, which is the most characteristic for the creep of heat-resistant materials. For low-plastic intermetallics, the influence of temperature and loading force on creep curves was studied. The dependences deformation rate vs time on the first and second stages of creep were obtained from bending tests. Thermal activation parameters are defined for the stage of permanent creep. The proposed method allows to study the speed sensitivity and to determine the thermal activation parameters of creep. In extreme conditions of operation of low-plastic heat-resistant materials, the proposed method allows to take into account and analyze the contribution to the creep of cracking and slow destruction processes. Keywords: three-point bending test, rate of deformation, initial stages of creep,high temperature materials, thermal activation parameters.

Grain Refinement of Cast Aluminum by Heterogeneous Nucleation Site Particles with High Lattice Matching

A number of studies have been carried out to identify the mechanism of grain refinement in cast aluminum alloys by addition of grain refiners containing potent heterogeneous nucleation site particles. Although some mechanisms and theories have been proposed, in this review, the role of heterogeneous nucleation site particles on grain refining performance will be focused. The content of this article is as follows. First, the morphology of Al3Ti particles in the Al–Ti refiners is presented, since the grain refining performance of the Al–Ti refiners is affected by the morphology of the Al3Ti particles. Evaluation methods of lattice matching between heterogeneous nucleation site and crystallized phase are, then, discussed. Since we conclude that M value is potentially applicable to predict the effective heterogeneous nucleation site, M value at elevated temperatures is described. Next, fragmentation behavior of Al3Ti particles caused by deformation of the refiners is presented, because the number density of the Al3Ti heterogeneous nucleation site particles is increased by the fragmentation of Al3Ti particles. At the same time, the morphology of the Al3Ti particles, which affects the grain refining performance, can be changed. The concept of grain refiners with high-symmetry L12 modified (Al1−xMex)3Ti intermetallic compound particles, fabrication method and some results on grain refining performance are also given. Finally, application of heterogeneous nucleation for other fields are described.

Waterjet Cutting of Permanent Magnets from Fe–Co–Ni–Cu–Al–Ti Alloys

Waterjet Cutting of Permanent Magnets from Fe–Co–Ni–Cu–Al–Ti Alloys

Functional Properties of Highly Textured Fe–Ni–Co–Al–Ti–B Shape Memory Alloy Wires

Functional Properties of Highly Textured Fe–Ni–Co–Al–Ti–B Shape Memory Alloy Wires

An ab initio molecular dynamics study on Ti2AlN(0001) surfaces

The structures, surface energies, electronic properties of Ti2AlN(0001) surfaces at 0 K-1273 K were systematically investigated by ab initio molecular dynamics and first-principles calculations. It is found that the structural relaxations of Ti(N)- and Ti(Al)-terminated surfaces at all temperatures are mainly confined between outermost two layers, and those of N(Ti)- and Al(Ti)-terminated surfaces with Ti atoms at second layer extends into third layer. N(Ti)-terminated surface experiences the largest relaxation, and Al(Ti)-terminated surface possesses the least relaxation and is the most stable surface at all temperatures. The structural shrinkage relaxation of outermost two layers and surface energy for N(Ti)- and Ti(N)- terminated surfaces keep relatively stable from 0 K to 933 K, whereas dramatically increase from 933 K to 1273 K. The relaxation of outermost two layers for Al(Ti)- and Ti(Al)-terminated surfaces changes owing to the thermal expansion of the d-spacing of Al-Ti layers. The larger thermal expansion coefficient of the d-spacing of Al-Ti layers and faster surface energy decline of Ti(Al)-terminated surface than those of Al(Ti)-terminated surface indicate stronger metallic properties. The influence of redistribution of Ti-3d, N-2p and Al-3p orbitals on the electronic properties and structural relaxations of different termination surfaces at all temperatures range is elucidated.

Effects of aluminum and oxygen additions on quenched-in compositional fluctuations, dynamic atomic shuffling, and their resultant diffusionless isothermal [formula omitted] transformation in ternary Ti–V-based alloys with bcc structure

Diffusionless isothermal ω transformation is a recently discovered ω transformation that occurs isothermally during aging near room temperature in Ti alloys with a bcc (β-phase) structure. Unlike conventional displacive phase transitions, the diffusionless isothermal ω transformation occurs in locally unstable nanoscale β-phase regions formed by quenched-in statistical compositional fluctuations. In the present study, the effects of Al and oxygen additions in ternary β-phase Ti–V-based alloys on the diffusionless isothermal ω transformation and its attempt process, called dynamic atomic shuffling, were studied. Elastic constant and internal friction measurements for Ti–16.6V–2.1Al and Ti–17.5V–2.5O (at.%) alloy single crystals and analysis of quenched-in compositional fluctuations using the thermodynamic theory of fluctuations indicated that the oxygen addition increases the β-phase stability, and it selectively increases the activation energy of dynamic atomic shuffling in locally unstable Ti-rich regions, which is caused by the strong attractive interaction between Ti and oxygen elements. As a result, oxygen addition suppresses the diffusionless isothermal ω transformation that occurs during aging at 298 K. In contrast, low β-phase stability, which promotes ω-phase nucleation, is retained by Al addition. Furthermore, dynamic atomic shuffling with a low activation energy is retained even though the average activation energy is enhanced by the Al addition, originating from the relatively weak atomic interaction between Ti and Al. Therefore, the diffusionless isothermal ω transformation cannot be suppressed by Al addition.

Effect of TiAlNbCrSi Alloy Microstructure Produced by Mould Casting (MC) or Electron Beam Powder Bed Fusion (EB-PBF) on Scale Grown Under Dry Air and Steam

TiAl parts fabricated with additive manufacturing have begun to find applications in car and aviation industry. Optimization of their properties concentrates on introduction of new alloying additions improving the TiAl ductility and oxidation resistance. Their effect on the mechanical properties was worked out quite well, but the knowledge how they affect the oxidation processes is still limited. Therefore the present experiment was aimed at investigation of scale grown over mould cast (MC) and electron beam powder bed fusion (EB-PBF) Ti–48Al–2Nb–0.7Cr–0.3Si (at. pct) alloys. It was conducted at 650 °C for 1000 hours both in dry air and steam covering early stages of this process. The scale microstructure, chemical and phase composition was examined with the transmission electron microscopy (TEM). Applied treatment caused development of three-layer scale, i.e. with major portions of R-TiO2 + α-Al2O3/R-TiO2/α-Al2O3. The one formed during dry-air oxidation of the EB-PBF alloy was most compact. Steam oxidizing changed morphology of rutile present at its surface from rod/plate-like into whiskers. The Si turned out to be especially active during scale growth diffusing up to its surface. The presence of steam further increased mobility of both Si and Cr rising their presence in the upper part of the scale. The Nb was found to accumulate within the substrate area adjoining to the scale. Refinement of EB-PBF microstructure as compared with the MC alloy resulted in promoting reaction at the scale/substrate front contributing significantly to development of thicker oxide coating and nitrides bearing oxidation affected zone.

Effect of Mo content on the microstructure, superplastic behavior, and mechanical properties of Ni and Fe-modified titanium alloys

Novel titanium-based alloys are required to increase the efficiency of superplastic forming technology and decrease energy consumption. For this purpose, the superplastic deformation behavior, strain-induced microstructure evolution in a temperature range of 625–775 °C, and post-deformation mechanical properties of Ti–4Al–1V–1Fe–1Ni-0.1B-xMo alloys (x = 1, 2.5, or 5 wt%) were investigated. The studied alloys demonstrated a stable flow with a high strain rate sensitivity coefficient m of 0.50–0.65 and an elongation-to-failure δ of 700–1000% at temperatures of 700–775 °C. Molybdenum insignificantly influenced superplastic deformation behavior at high temperatures due to a high fraction of the β phase of 22–62%. The Mo effect was significant at a low deformation temperature of 625 °C. At this temperature, an increase in Mo content from 1 to 5% provided the β-phase fraction above the critical value of ∼20% and increased the m-value from 0.4 to 0.5 and δ from ∼200 to ∼700%. Increasing Mo from 1 to 5% enhanced the post-deformation yield strength at room temperature by 180 MPa, the ultimate tensile strength by 170 MPa, and the ductility by 2.5%. Consequently, alloying Ti–4Al–1V–1Fe–1Ni-0.1B with 5% Mo provided an excellent combination of superplasticity at a low temperature of 625 °C and post-forming tensile mechanical properties.