Niobium Content Research Articles

Improved the microstructures and properties of W−Mo−V high‐speed steel by laser additive manufacturing and niobium alloying

AbstractIn engineering applications, improving the properties of high‐speed steel (HSS) has long been a focus of research. Niobium (Nb), as a strong carbide forming alloy element, is conventionally added to steels to improve their mechanical properties. In the present work, W−Mo−V high‐speed steel were deposited by laser additive manufacturing with the aim of investigating the effects of niobium content on the microstructures and mechanical properties. And the niobium content was varied between 0 wt % and 2 wt %. The results show that the content of niobium has a greater influence on the microstructure and mechanical properties of the samples. In particular, with addition of niobium element, the W−Mo−V high‐speed steel samples presented a more refined and uniform microstructure compared to the niobium‐free sample. Moreover, the addition of niobium can increased the deposition of niobium‐rich MC‐type carbides in the microstructure and improving the microhardness of W−Mo−V high‐speed steel, and also can increased the wear resistance and ductility. Especially for 2 wt % niobium sample, it has excellent wear resistance and high elongation, which were improved by 43.1 % and 32.6 % respectively compared to the W−Mo−V high‐speed steel sample.

Use of first principles and Thermo-Calc to identify potential low elastic modulus titanium-based alloys for biomedical applications

High alloyed β-phase stabilised titanium alloys are known to have low elastic moduli comparable to that of the human bone (≈30 GPa). The β-phase in titanium alloys exhibits an elastic modulus of about 60-80 GPa, which is nearly half that of α-phase (100-120 GPa). In this work, an attempt to develop a β-phase titanium-based alloy through first-principles calculations and Thermo-Calc calculations for biomedical applications was conducted. First-principles calculations were performed using the CASTEP code on a simple 2-atom bcc unit cell to predict the theoretical elastic modulus and mechanical stability of the Ti-Nb-Ta-Zr (TNTZ) system at 0 K. Thermo-Calc was used to determine the phase proportion diagrams of the proposed alloys at 500℃. The alloy comprised Ti-Nbx-Ta25-Zr5 (x = 5, 10, 20, 30, 40) (at.%). The theoretical results suggested that increasing niobium content introduced both mechanical (cʹ > 0) stability of the alloys. Alloy Ti-Nb5-Ta25-Zr5 gave the lowest elastic modulus of 55.23 ± 24.45 GPa which is half the elastic modulus of pure titanium (α phase). The phase proportion diagrams showed that up to 58.6 mol.% of β phase was retained at 20 at.% Nb, although the Voigt-Reuss-Hill Young’s modulus calculated from first principles increased with increasing niobium content while the α/β phase transformation temperature decreased down to 551.3℃ at 40 at.% Nb.

Laves phase precipitation and sigma phase transformation in a duplex stainless steel microalloyed with niobium.

Duplex stainless steels are used to replace austenitic steels in industrial applications, especially in the chemical industry where corrosion resistance in chloride-containing media is an important requirement. According to literature, niobium has a great influence on the transformation of the phases of these steels (ferrite, austenite and sigma). Given the interest in evaluating this property in terms of wear resistance and corrosion of the material, the aim of this study was to evaluate the effect of niobium on the formation in austenitic-ferritic stainless steel SEW 410 Nr 1.4517 after heat treatment at 850ºC for 15, 30 and 60 minutes. The niobium contents studied were 0.2; 0.5 and 1.5 wt%. Measurements of microhardness, electrochemical tests in saline solution containing 3.5% sodium chloride and wear resistance were carried out. The results show that an increase in niobium content and sigma phase leads to an increase in hardness and wear resistance, associated with a decrease in corrosion potential. Therefore, the use of niobium in austeno-ferritic stainless steel is recommended when wear resistance is an important factor to be considered.

Structural, dielectric and energy storage properties of BaO–Na2O–Nb2O5–P2O5 glass-ceramics

A series of (1−x)[(2BaO–0·5Na2O)–1P2O5] –xNb2O5 (BNPN, x=0·41, 0·43, 0·45, 0·48) glass-ceramics based on phosphate glasses have been prepared via a controlled-crystallisation route. The structure, dielectric properties, interfacial polarisation and energy storage properties were systematically investigated. The x-ray diffraction results showed the simultaneous presence of Ba2NaNb5O15 tungsten bronze structure (TTB) and the NaNbO3 perovskite. A stable dielectric constant over a temperature range from 25–200°C, low dielectric losses less than 0·03 and excellent frequency stability at room temperature were obtained. The decrease of niobium content promoted the TTB crystallisation with improvement of the high dielectric properties of the system. The optimum of the dielectric constant and recoverable energy storage density were obtained for BNP41 crystallised at 1000°C. Analyses of the complex impedance indicated that the niobium content and crystallisation temperature affect the interfacial polarisation.

Influence of aluminium and niobium alloying on phase composition, structure and properties of heat- and wear-resistant cast iron of Cr-Mn-Ni-Ti system

The paper presents the data on phase composition and structure forming for the alloys and oxide layers, on distribution of elements among the alloy structural components and oxidation surface through the depth of oxide and sub-oxide layers, on variation of wear resistance, scale resistance, growing stability and mechanical properties of cast iron of Cr-Mn-Ni-Ti-Al-Nb system depending on different aluminium and niobium content and thermal accumulating capacity of a casting mould. Complex carbides (Nb, Ti)C are forming in white cast iron during niobium alloying. Quantitative metallographic analysis of (Nb, Ti)C carbides and (Cr, Fe, Mn)7C3 complex carbides was carried out on the samples with examined composition. The tests for scale resistance were conducted, structure and properties of cast iron were investigated. It was determined that chemical composition and structure of oxide layers depend on distribution of alloying elements among the alloy structural components. It was established that the areas of oxide film surface layer, which were formed on eutectics, contain mainly manganese; its concentration is more than 65 %, while Al is 4 % and Cr is 1 %. Manganese leads to increase of defects amount, such as pores, micro-cracks and vacancies, in oxide film during high-temperature gas oxidation; penetration ability of this film also increases, what has a negative effect on metal resistance to further destruction caused by oxidation. The film becomes porous, its thickness enlarges. Aluminium provides favourable influence on forming of the thin protective spinel-type films (dense substance with good metal adhesion) with minimal amount of defects; diffusion through such oxide film is very difficult. The areas of oxide layer, which were formed on austenite dendrites, contain mainly aluminium; its concentration is more than 24 %, while Mn is 16 % and Cr is 12 %. High aluminium content provides small film thickness. Joint alloying by aluminium and niobium leads to simultaneous increase of heat resistance and wear resistance. Wear resistance increased as a result of enlargement of the part of primary carbides (Nb, Ti)C with high hardness in the structure of cast iron. Composition of oxide films includes aluminium which strengthens their protective properties and rises of the alloy scale resistance. Alloying by niobium leads to secondary hardening during cooling in a casting mould. Dispersion particles of М7С3 carbides are forming in solid state, thereby no structure degradation occurs during testing at increased temperatures, and growing stability rises.

Controlling the tribology performance of gray cast iron by tailoring the microstructure

Addition of rare metal is an interesting way of microstructural controls. Herein, this study employed niobium to tailor the microstructure of gray cast iron, and further to control the tribology properties. Four casting discs with various niobium contents (0~0.31wt.%) were prepared to slide against one certain resin-based friction material. Friction test was performed on a 1:5 scale brake inertia dynamometer under different conditions. Results revealed the significance of niobium concentration on the microstructure by influencing the solidification process. Consequently, a modification to the mechanical and thermal properties was achieved, which was responsible for subsequent tribology behavior. Overall, 0.20wt.% was defined as the optimized formulation of a lower sensitivity to operating conditions, higher brake efficiency, and higher wear resistance.

Influence of Nb on the Structure and High Temperature Performance of Billet for High-Rise Structural Steel

Reasonable control of the niobium (Nb) content in steel slabs is of great significance for improving the surface quality of the slabs. In this study, a Gleeble-3500 thermal simulation testing machine was used to test the high-temperature mechanical properties of steel slabs with four different Nb contents (A: 0.006%, B: 0.031%, C: 0.050%, D: 0.065%) and to analyze the effect of Nb on the high-temperature performance of the steel slabs. Optical microscopy and transmission electron microscopy (TEM) were used to study the microstructure of the casting slabs with different Nb contents and the precipitation in the samples after heat treatment at different temperatures. The results of the study show that the microstructure of the cast slab is mainly composed of ferrite and pearlite. The distribution of each of the two structures was found to become more uniform and a significant improvement in yield strength was observed with increasing Nb content. After heat treatment, the precipitates in the high-rise structural steel were mainly square and star shaped Nb(C,N) precipitates. Increasing the Nb content was found to increase the amount of precipitates in steel. Beyond a threshold, increasing the Nb content did not increase the amount of precipitates. However, the size of the precipitates increased.

On the Impact of the Intermetallic Fe2Nb Laves Phase on the Mechanical Properties of Fe-6 Al-1.25 Nb-X W/Mo Fully Ferritic Light-Weight Steels

The present study aims at the development of precipitation hardening fully ferritic steels with increased aluminum and niobium content for application at elevated temperatures. The first and second material batch were alloyed with tungsten or molybdenum, respectively. To analyze the influence of these elements on the thermally induced precipitation of the intermetallic Fe2Nb Laves phase and thus on the mechanical properties, aging treatments with varying temperature and holding time are performed followed by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) including elemental contrast based particle analysis as well as hardness measurements and tensile tests at room temperature and at 500 °C. The incorporation of molybdenum into the Laves phase sets in at an earlier stage of aging than the incorporation of tungsten, which leads to faster growth and coarsening of the Laves phase in the molybdenum-alloyed steel. Nevertheless, both concepts show a fast and massive increase in hardness (280 HV10) due to precipitation of Laves phase during aging at 650 °C. After 4 h aging, the yield strength increase at room temperature is 100 MPa, which stays stable at operation temperatures up to 500 °C.

The Precipitation of Niobium Carbide and Its Influence on the Structure of HT250 for Automobile Wheel Hubs

Improving the strength of grey cast iron wheel hubs will improve the safety of automobiles and have a great significance for energy saving and environmental protection. This paper systematically compares the calculation results of Python-based precipitation calculation and JmatPro software simulation with experiments. The results show that with a low mass fraction of niobium (0.098%) cuboid Niobium Carbide (NbC) precipitates do not form in the liquid phase; however, an elongated NbC niobium-rich phase may form during the solidification process and in the solid phase. However, cuboid NbC precipitates can be precipitated from the liquid phase when the niobium mass fraction is higher (0.27%, 0.46%). These results indicate that with the increasing niobium content the amount, particle size, and initial precipitation temperature of niobium carbide precipitated in the matrix structure will increase. According to the observation and statistical analysis of the microstructure, it is found that tensile strength will be improved with an increase in niobium content due to the refinement of the graphite and pearlite interlamellar spacing. In this paper, adding less than 0.32% of Nb to grey cast iron is recommended, considering the comprehensive cost and the effect of niobium in the material structure.

Comparison of Microstructure and Mechanical Properties of High Strength and Toughness Ship Plate Steel.

E36 ship plate steel was, respectively, produced by as rolling and normalizing process (ARNP), and EH36 and FH36 ship plate steel was produced by the thermo-mechanical control process (TMCP) with low carbon and multi-element micro-alloying. The microstructure of the three grades of ship plate steel was composed of ferrite, pearlite, and carbides at room temperature. The average grain size on 1/4 width sections (i.e., longitudinal sections) of the three grades of ship plate steel was, respectively, 5.4 μm, 10.8 μm, and 11.9 μm. EH36 and FH36 ship plate steel had the higher strength due to precipitation and grain boundary strengthening effect, while the E36 ship plate steel had the lower strength due to the recovery phenomenon in the normalizing process. EH36 and FH36 ship plate steel had higher impact toughness due to lower carbon (C) and silicon (Si) content and higher manganese (Mn) content than E36 ship plate steel. E36 ship plate steel had the best plasticity due to the two strong {110} and {111} texture components. The fracture toughness KJ0.2BL(30) values of E36 and EH36 and KJ0.2BL value of FH36 ship plate steel were, respectively, obtained at 387 MPa·m1/2, 464 MPa·m1/2 and 443 MPa·m1/2. EH36 and FH36 ship plate steel had higher KJ0.2BL(30) due to lower C and Si and higher Mn, niobium (Nb), vanadium (V), and aluminum (Al) content than the E36 ship plate steel. The fatigue crack growth rate of E36 ship plate steel was higher than that of EH36 and FH36 ship plate steel due to its higher carbon content and obviously smaller grain size. The analysis results and data may provide a necessary experimental basis for quantitatively establishing the relationship between fracture toughness, yield strength and impact toughness, as well as the relationship between fatigue crack growth rate and both strength and fracture toughness.

+Effect of niobium on microstructure and properties of 6016 aluminum alloy

6016 aluminum alloys with different niobium contents were prepared by smelting and casting. The alloys were rolled and heat treated, and the effect of niobium on microstructures and properties of the alloys were studied. The results show that the as-cast alloy consists of Mn-rich phases, Cu-rich phases, Mg-rich phases, Si-rich phases and small blocks of Zn-rich phases, and Nb element is solidly dissolved in these phases and matrix. After solution and pre-aging treatment, recrystallization occurs in the rolled alloy. The grain size of the rolled alloy is obviously smaller than that of the as-cast alloy, and the second phase precipitates dispersively. After solution treatment or solution treatment + pre-aging treatment, the tensile strength and plasticity of the alloy are significantly improved. With the increase of niobium content, the number and size of the second phase increase. The alloy with 1%Nb in T4P condition has the better comprehensive mechanical properties, and its elongation after fracture, tensile strength, yield strength, plastic strain ratio and strain hardening index are as following respectively: 34.20%, 372.77MPa, 208.54MPa, 0.82, 0.32.

Adjustable electrochemical properties of solid-solution MXenes

MXenes are promising pseudocapacitive materials with ultrahigh specific capacitance. Currently, more than 30 stoichiometric MXene compositions and about 20 solid solutions have been experimentally synthesized. However, most studies focus on Ti 3 C 2 T x or a few other single-M MXenes, and little is known about the electrochemical properties of solid-solution MXenes. Herein, two sets of niobium-based solid-solution MXenes (Ti 2−y Nb y T x and V 2−y Nb y T x ; 0 ≤ y ≤ 2) were synthesized and the dependence of their electrochemical properties on the ratio of M elements in the structure was investigated. Relationships between the chemistry and charge storage ability, including capacitive properties and cycling stability in aqueous protic electrolyte, were determined. There is an inverse relationship between the prominence of the redox peaks and cycling stability; the latter increases with the niobium content. For instance, the capacitance retention after 20,000 cycles is less than 1% for Ti 2 CT x , but 78% for Ti 0.4 Nb 1.6 CT x . This study shows that electrochemical properties of MXenes can be controlled by tuning the ratio of transition metals in the MXene structure. • Double-metal solid-solution MXenes (Ti 2−y Nb y T x and V 2−y Nb y T x ; 0 < y < 2) were synthesized and investigated. • The capacitive properties and cycling stability of solid-solution MXenes directly depend on their composition. • The redox peak intensity decreases while the cycling stability increases with the Nb content. • This study provides a guide for adjusting the electrochemical properties of MXenes by tuning the M-site chemistry.

Quantitative analysis of microstructure and mechanical properties of Nb–V microalloyed high-strength seismic reinforcement with different Nb additions

Abstract HRB500E seismic steel bars are mainly used in high-rise buildings near the seismic zone. The influence of different niobium contents (0–0.023%) on the microstructure and mechanical properties of HRB500E seismic reinforcement was studied. Results showed that the grain size of ferrite was between 3.6 and 8.3 μm when only V was added. Meanwhile, as the niobium content increases, the ferrite particles are further refined. After adding niobium, the grain contribution increased by 9%. The addition of niobium significantly refined the grain size of HRB500E seismic reinforcement. The second-phase nano-elliptic precipitate is NbC. The precipitated phase is dispersed on the grain boundary and the matrix, and the dislocation density on the matrix promotes the precipitation of NbC particles along the dislocation line. The second-phase precipitation of niobium can form an effective pinning effect and then refine the pearlite spacing. The microhardness and the tensile strength also significantly improved. The yield strength increased from 509 to 570 MPa.

Complex, multi-stage mineralization processes in the giant Bayan Obo REE-Nb-Fe deposit, China

The Bayan Obo REE-Nb-Fe deposit with giant rare earth reserves, still has no unified understanding of the REE and Nb-bearing mineral evolution and the division of mineralization stages, due to the complicated metallogenic process and the huge controversy on the important issues such as the origin of ore-hosting dolomite. In this work, the whole process of carbonatite magma solidification and mineralization is divided into six stages: coarse dolomitic facies, fine dolomitic facies, disseminated mineralization, banded mineralization, massive mineralization and vein mineralization. The mineralogical composition and paragenesis of various types of rocks and ores have been systematically studied using the automatic mineral analysis technology-Advanced Mineral Identification and Characterization System (AMICS), supplemented by optical microscopy and cathodoluminescence. In order to establish the internal relationship between different stages, trace elements of six kinds of rocks and ores were analyzed. The mineralogical studies show that the rare earth minerals appear in the order of transition from the phosphate minerals in the brine-melt stage (fine dolomitic facies), through the fluorcarbonate minerals in the hydrothermal stage (disseminated, banded and massive mineralization), to the Ba-fluorcarbonate minerals in the Paleozoic vein mineralization, and all of these are generally associated with apatite, baryte, fluorite, aegirine and quartz. The distribution of niobium minerals in all kinds of ores is in the form of disseminated grains, and there is no obvious paragenetic relationship with other minerals, which indicate that niobium mineralization may only be related to the content of niobium in hydrothermal solution. The geochemical data show that all types of rocks and ores have positive anomalies of Ba and Nb, negative anomalies of U, Ta, Sr, Zr and Y. From coarse dolomitic facies to massive mineralization, the content of REE, Nb and Th increases, the content of Sr decreases, and the ratio of (La/Yb)N and (La/Nd)N increases, all of which change continuously. Vein mineralization has similar (La/Nd)N and (La + Ce + Pr)N/REE ratios compared with coarse dolomitic facies and has a wide range of Sr, Th, Nb and REE compositions, and elemental ratio and content of vein mineralization are within the distribution range of ore-hosting dolomite and different types of mineralization. Based on the above, it is considered that the main mineralization body at Bayan Obo was formed in the process of auto-metasomatism of Mesoproterozoic igneous carbonatite, while vein mineralization was the product of homogenization and re-precipitation of early ore-forming material by the Paleozoic fluids, without the addition of exogenous metallogenic materials.

Sensitivity of mechanical properties of pipeline steels to microalloying additions and structural characteristics

This study assesses the effect of microalloying additions and thermomechanical processing on the mechanical properties of four pipeline steels. The investigated steels had quite similar processing conditions, with some small differences, in niobium (Nb) content. The surface and center layers of the steels were characterized after thermomechanical processing, using X-ray diffraction, electron backscatter diffraction and mechanical tests. The surface layers of the steels showed shear textures, {011}<100> and {011}<211>, while conventional rolling textures were observed in the center layers. However, the steel with a very low Nb content displayed relatively stronger rotated cube {001}<110> component and a bimodal grain size distribution on the surface. Interestingly, compared to the other steels, a more significant difference in the local strain distribution, as well as the percentage of deformed and recrystallized grains, was observed between the surface and center layers of this low Nb steel. These small differences in microstructure and texture resulted in a considerable reduction in the strength and low temperature impact toughness by over 10%. Additionally, the importance of strain accumulation to the intensity of crystallographic texture was also observed. The results of this study clearly illustrate the complex interaction between thermomechanical processing and microalloying additions, which leads to differences in microstructure, texture and subsequently, the mechanical properties of steels.

Investigation on the Correlation between Piezoelectricity and Its Thermal Behavior with Depolarization Temperature and Antiferroelectric Order in Niobium‐Doped (Na0.41K0.09Bi0.5)TiO3: A Lead‐Free Piezoelectric

A correlation between piezoelectric response and its thermal stability with the depolarization temperature and antiferroelectric order in (Na0.41K0.09Bi0.5)(1−x/2)(Ti1−xNbx)O3 (x = 0.00–0.0150) ceramic is investigated. A reasonable increase in the piezoelectric response (20–25%) is observed in a limited composition range (0.0050 ≤ x ≤ 0.010). The piezoelectric thermal stability for the lower niobium concentrations (x &lt; 0.010) is found to be reasonably better than many archetypal lead‐free piezoelectrics. However, a significant thermal instability is observed for the higher niobium content (x ≥ 0.010). The observed thermal instability is attributed to the monotonic decrease in the depolarization temperature with the emergence of antiferroelectric ordering in the vicinity of the ferroelectric‐relaxor crossover region. The increase in the piezoelectric response in the aforementioned composition range is associated with the competition among the ferroelectric domain wall movement and the antiferroelectric order. The outcome of the current study reveals that (Na0.41K0.09Bi0.5)(1−x/2)(Ti1−xNbx)O3 with x = 0.005 is a useful lead‐free piezoelectric with consistent thermal response.

Structure, dielectric, and energy storage behaviors of the lossy glass-ceramics obtained from Na2O-Nb2O5-P2O5 glassy-system

ABSTRACT A series of phosphate glasses defined by the composition 50Na2O-xNb2O5-(50-x)P2O5 (0<x < 25 mol%) and designated as Nb5, Nb10, Nb15, Nb20, Nb25, respectively, have been elaborated by the melt quenching method, and their structural and optical properties were investigated. It was found that their density and molar volume increase and decrease with the Nb2O5 content, respectively. The analysis of the glasses structure by Raman spectroscopy allowed the identification of several phosphate structural units, mainly metaphosphate and pyrophosphate, and showed that niobium adopts an octahedral oxygen environment, forming linkages such as Nb-O-P and Nb-O-Nb within the network. Glass-ceramics were obtained by controlled heat treatments of the parent glasses. The heat treatment of the high niobium concentration glass Nb25 at 650°C led to the formation of the sodium niobate phase with cubic symmetry. Its microstructure was analyzed by SEM. The study of the dielectric properties of the glass-ceramics and their energy storage performance presented an optimum discharge density for the glass-ceramic with 25 mol% Nb2O5 and an energy efficiency of 82.5%.

Oxidation behaviors of (Ti1-xNbx)C ceramic solid solutions

(Ti1-xNbx)C (x=0, 0.2, 0.5 and 0.8) ceramic solid solutions were prepared by spark plasma sintering and their oxidation behaviours were investigated at 1000 °C in air. The niobium content was found to exhibit a remarkable influence on the oxidation resistance of (Ti1-xNbx)C solid solutions. An optimization of oxidation resistance was achieved in (Ti0.8Nb0.2)C. After oxidation at 1000 °C for 4 h, the oxidation layer thickness of (Ti0.8Nb0.2)C is less than 1/4 of the oxidation layer thickness of monolithic TiC. The higher oxidation resistance can be ascribed to the presence of Nb-doped rutile TiO2 phase in the oxidation layer of (Ti0.8Nb0.2)C. The (Ti,Nb)O2 phase suppressed the abnormal grain growth and the formation of cracks in the oxide layer, more importantly, it could effectively sluggish the outward diffusion of titanium during oxidation.

Study on gamma radiation attenuation and non-ionizing shielding effectiveness of niobium-reinforced novel polymer composite

Advanced radiation applications have been widely used and extended to many fields. As a result of this fact, choosing an appropriate shielding material based on the radiation application has become vital. In this regard, the integration of elements into polymer composites has been investigated and contributed to the quantity and quality of radiation shielding materials. This study reports photon attenuation parameters and electromagnetic shielding effectiveness of a novel polymer composite prepared with a matrix reinforced with three different proportions (5, 10, and 15 wt%) of niobium content. Addition of Nb dopant improves both photon attenuation and electromagnetic shielding effectiveness for the investigated composites. Therefore, Nb(15%) polymer composite with highest concentration has been found to be the best absorber for ionizing and non-ionizing radiations. Consequently, the performed analyzes provide evidences that the prepared Nb-reinforced polymer composite could be effectively used as photon radiation attenuator and electromagnetic shielding material.

Achievement of forging without canning for β-solidifying γ-TiAl alloy containing high content of niobium

ABSTRACT The processes of forging without canning were optimized, such that forging could be successfully performed and forged pancakes without cracks could be obtained. The maximum height reduction could reach 80%. The as-forged microstructure consisted of γ and β/B2 phases. The volume fraction of the β/B2 phase rose slightly compared to the pre-forging state. Near the top or bottom of the pancake, residual lamellae were found, while full dynamic recrystallization was completed at the center and lateral parts. Equiaxed γ grains illustrated that dynamic recrystallization mainly occurred in the γ phase, while the softer β phase coordinated the deformation by adjusting morphology. Two types of Σ3 boundaries, [110] 70° and [111] 60°, were found in the γ phase. At room temperature, the fracture was brittle, and the elongation was 0.07%. With increasing temperature, the yield strength and ultimate strength decreased, while the elongation increased. The brittle–ductile transition temperature was between 800°C and 850°C.