Substantial Increase In Hardness Research Articles

Tracking research on the performance changes of S31042 steel under long term service

S31042 is widely used in ultra-supercritical units due to its excellent comprehensive performance at high temperatures. Tracking and monitoring research was conducted on as-received S31042 tubes and tubes in service for 13k hours, 31k hours, and 52k hours at 650 °C. The results show that as the service time increased, a large quantity of M23C6 phase precipitated along the grain boundaries, gathered and grew up into the bulk. This weakened of the grain boundaries, which facilitated crack propagation and significantly reduced the plasticity and toughness of the S31042 heat-resistant steel. After 13k hours of operation, the dispersion strengthening of the precipitated phase inside the grain and grain boundary led to a substantial increase in hardness, while there was no obvious change in strength. However, after 52k hours of operation, the dispersed precipitated phase within the grain slowly aggregated and grew, decreasing the effectiveness of dispersion strengthening. Consequently, both the high-temperature strength and hardness of the S31042 steel gradually decreased. As the service time increased, the continuously distributed and similarly sized M23C6 phases on the grain boundaries of S31042 developed into an inhomogeneous coarsening chain structure. Additionally, the appearance of nanoscale secondary NbCrN and M23C6 phases within the grain and their resulting precipitation strengthening effects were the main reasons for the significant change in S31042 hardness values. Based on these findings, the residual life of S31042 heat-resistant steel in service was predicted using an extrapolation method based on high-temperature creep rupture tests and the relationship model between hardness and the P function. A comparison of the L-M parametric life prediction results with the strength extrapolation life prediction results based on the standard creep rupture test shows that the creep rupture strength extrapolation method is slightly conservative. Therefore, the prediction results based on the hardness L-M parameter method, which is simple and easy to perform, can be used for preliminary life prediction.

Boron Enhanced Complex Concentrated Silicides – New pathway for designing and optimizing ultra-high temperature intermetallic composite materials

Refractory Metal Intermetallic Composites and Refractory Complex Concentrated Alloys have been identified as promising candidates for ultra-high-temperature applications that exceed the limits of superalloys. However, designing and developing new materials with the proper density for aerospace applications is a significant challenge. For this reason, new refractory metal-based materials are in continuous development. This study introduces a new class of materials known as Boron-Enhanced Complex Concentrated Silicides (BECCSs). By providing a balance between density and high-temperature performance, these materials with their density-optimized refractory metal silicide-borides have the potential to revolutionize high-temperature applications. Utilizing a quaternary MoNbTaW equiatomic alloy (ρ = 13.73 gcm−3) as a starting point and a computer-aided alloy modeling tool, seven alloy compositions were designed in a multi-step process aimed at lowering the material density. Through the introduction of Ti, Si, and/or B, the microstructure was transformed from a BCC solid solution to a multiphase structure comprised of silicides and borides. The proposed redesign of the alloy led to a significant reduction in density, even to 5.44 gcm−3. All seven alloys were produced by using a laboratory arc melter, and their microstructure and room-temperature mechanical properties were analyzed using SEM, EDS, EBSD, and micro-indentation. The results of structural characterization allowed us to identify specific phase constituents, and it was established that a transition from BCC solid solutions to silicides/borides-based alloys results in a substantial increase in hardness, even above 1600 H V (17 GPa).

Characterization of Iron Aluminide Diffusion Coatings Obtained after Friction Surfacing

Iron aluminides are considered as candidate materials for high temperature applications for their excellent high temperature corrosion and oxidation resistance. In the present work, iron-aluminide coatings were developed by friction surfacing (6351 aluminum alloy deposited on a low-carbon steel substrate) followed by a diffusion heat treatment. The initial coatings were found to be geometrically homogenous and adhered well to the steel substrate. The heat treatment process was carried out at 550 °C for 48, 72 and 96 h and the resulting coatings were characterized in terms of microstructure, chemical composition, hardness distribution and phase composition. After heat treatment, the coating/substrate interface morphology was modified and presented patterns typical of Fe-Al intermetallic formation, as well as a substantial increase in hardness (>900 HV) relative to the initial as-deposited condition. With the diffusion treatment, initially Fe2Al5 was found to develop in the coatings, which was converted into FeAl2 after longer exposures.

Laser assisted cold spray of 15–5 PH stainless steel in a designed and developed setup

Laser Assisted Cold Spray (LACS), a hybrid deposition process can be used to deposit crack free coatings in solid state with high compressive residual stress for variety of materials. However, high gas consumption rate, high maintenance cost, and costly experimental set-up often restricts its widespread usage in industries. The present work attempts to address these challenges. A novel design for a compact supersonic nozzle has been conceptualized and fabricated. The nozzle is designed for 2 Mach gas velocity having Converging- Diverging- Barrel (C-D-B) typed shape in which powders are injected in the barrel zone where the gas pressure ratio is minimum. Thus, it can be used with any commercially available low gas pressure powder feeder. The flow characteristics of the gas jet coming out of the nozzle have been characterized using a simple yet accurate home-built experimental setup. Gas velocity measured at the 5 mm standoff distance was ∼ 550 m/s, which compared well with the supersonic gas velocity estimated by measuring the gas jet temperature at the nozzle exit. Crack-free deposition of 15–5 PH Stainless Steel up to 220 µm layer thickness and an average compressive residual stress of 372 MPa was obtained on SS304 substrate. Substantial increase in hardness and scratch hardness,1.5 times and 2.5 times respectively, of the coating was obtained as compared to those of the substrate material. The coating could sustain upto 60 N load without producing any cracks during scratch test.

Phase decomposition upon heat-treatment of a eutectoid Ti-Fe alloy processed by dual-wire-arc additive manufacturing

Titanium alloys are among the most relevant structural materials for aerospace applications; they can be processed using various additive manufacturing (AM) techniques including wire-based AM. However, conventional alloy systems, such as Ti-6Al-4V, are, from a metallurgical perspective, not optimized for AM. Here, we investigate the effects of alloying Ti with Fe using dual-WAAM to improve the understanding of the effects of the addition of β-eutectoid forming elements on the microstructure. A structural characterization of the material after processing reveals the microstructure in the as-built condition to primarily consist of β-phase from which α-phase is precipitated upon a heat-treatment, resulting in a substantial increase in hardness.

Understanding the role of in-flight particle temperature and velocity on the residual stress depth profile and other mechanical properties of atmospheric plasma sprayed Al2O3 coating

This report deals with the influence of particle temperature and velocity on the microstructure, mechanical properties and residual stress depth profile of plasma sprayed alumina coating. The coatings were produced by varying the particle temperature while maintaining a relatively fixed particle velocity, and vice versa. Residual stress profiles were acquired by measuring the stress in successive layers using X-ray Sin2ψ technique. A substantial increase in hardness and indentation modulus by 76% and 64%, respectively were observed with an increase in particle temperature. With an increase in velocity, coating porosity was found to decrease initially. However, at a high velocity, porosity again increased to a limited extent. The mechanical properties were found to depend strongly on porosity. An increase in particle temperature resulted in an increase in the tensile residual stress in the coatings. Moreover, partial recovery of the grit blasted compressive substrate occurred during spraying owing to an annealing effect.

Thermally cross-linked ultra-robust membranes for plasticization resistance and permeation enhancement – A combined theoretical and experimental study

This study reports enhanced flux in plasticization-resistive ultra-robust membranes by thermally cross-linking a blend of carboxylated polyimide (PI) and ladder-like amino-polysilsesquioxane (LAPSQ). A series of BTDA-Durene:DABA PIs (BTDA: 3,3′,4,4′-benzophenonetetracarboxylic dianhydride) with three different 2,3,5,6-tetramethyl-1,4-phenylenediamine (Durene):3,5-diaminobenzoic acid (DABA) molar ratios (3:2, 2:1, and 4:1) exhibited an increase in gas permeability with an increasing Durene:DABA molar ratio before and after dehydration-induced cross-linking; this indicated that the bulky Durene moiety was more critical for flux enhancement than the number of carboxylated sites post-cross-linking. More importantly, the thermally cross-linked PI/LAPSQ (80/20) membrane exhibited a significantly enhanced CO 2 permeability of 817% than that of its pre-crosslinked counterpart without sacrificing CO 2 /N 2 or CO 2 /CH 4 selectivity due to a combination of decarboxylation and amidation-induced cross-linking. Molecular dynamics simulations revealed that such a drastic increase in CO 2 permeability was due to larger and/or more interconnected cavities formed in the thermally cross-linked PI/LAPSQ (80/20) membrane. In addition, it showed a substantial increase in hardness and reduced modulus owing to the rigid double-stranded siloxane backbone of LAPSQ and plasticization resistance up to a CO 2 feed pressure of 22 bar. ● Membranes were cross-linked by decarboxylation/amidation of a hybrid polymer blend. ● Siloxane backbone in cross-linked membranes increased hardness and reduced modulus. ● CO 2 permeability of hybrid membranes increased 817% after thermal cross-linking. ● MD simulations showed cross-linking forms larger and more interconnected cavities. ● Cross-linked hybrid membranes were plasticization resistant up to 22 bar of CO 2 .

Grain refinement effect on the Ti-45Nb alloy electrochemical behavior in simulated physiological solution

In this study, the influence of microstructural refinement induced by the high-pressure torsion (HPT) on the corrosion resistance of the Ti-45Nb (mass%) alloy was investigated. The alloy characteristics before and after the HPT deformation were analyzed by electron backscatter diffraction (EBSD), scanning transmission electron microscopy (STEM), x-ray diffraction (XRD), and Vickers microhardness measurements, while the alloy corrosion behavior in simulated physiological conditions was examined by potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS) analysis. Detailed microstructural analyses revealed that the HPT deformation led to significant grain refinement of the Ti-45Nb alloy exhibiting an ultra-fine grained (UFG) microstructure along with a substantial increase of hardness. Results also indicated that the grain refinement did not affect the alloy phase composition since β-Ti and Ti4Nb phases were present in the microstructure before and after the HPT deformation. Even though the Ti-45Nb alloy in both, coarse-grained (CG) and UFG, conditions shows high corrosion resistance in Ringer's solution at 37 °C, it was observed that the HPT treatment additionally improved the alloy corrosion properties. Namely, more rapid formation of the passivating layer with better barrier properties on the UFG alloy surface was recorded and resulted in better corrosion resistance of the alloy after HPT deformation. An increase of the grain contact area in the refined microstructure caused an increase of the diffusive transfer along the grain boundaries, accelerated the formation of a less defective protective barrier surface layer, and promoted the alloy surface passivation in the simulated physiological conditions.

Effect of microstructural constituents on mechanical properties and fracture toughness of Inconel 718 with anomalous deformation behavior at 650 °C

In the current work, Inconel 718 superalloy was subjected to five different heat treatment schedules to develop five different microstructures for studying the effect of γ’, γ” and δ phases on mechanical properties of IN-718 at room temperature and 650 °C as the working temperature of IN-718 is near 650 °C. Microstructural characterization was performed with Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Vickers hardness tests, tensile tests and fracture toughness (JIC) tests were performed for different heat-treated samples at room temperature. Further tensile tests were carried out at 650 °C for all heat-treated specimens and one high-temperature JIC test at 650 °C was performed for Standard heat-treated compact tension specimen. It had been demonstrated that γ′ and γ″ phases caused a substantial increase in hardness of the material while δ phase was attributed to low hardness of this superalloy. Also, it was found that γ″ phase provided maximum strength to IN-718 superalloy followed by γ′ at room temperature but on contrary, γ′ was found to be primarily responsible for higher strength than γ″ at 650 °C. The δ phase furnished poor strength at all temperatures. However, the formation of Nb + Ti carbides and oxides at 650 °C caused premature failure of the tensile specimens with lower elongation. In case of fracture toughness test, the maximum value of critical J-integral (JIC) and tearing modulus (T) were demonstrated by γ′ phase. A decrease in the JIC value of the material was observed at higher temperature (650 °C). Both critical J-integral (JIC) and tearing modulus (T) were found to be critical parameters for crack growth characterization of this superalloy.

Investigation on the mechanical properties of press-hardened boron steel sheets using the conductive heating technique

An aluminized 22MnB5 (Boron) steel sheet, used for structural parts in the automotive industry, was subjected to press-hardening followed by austenitizing, both in a conventional furnace and via the conductive (electric resistance) heating method, an innovative technique based on the Joule’s principle for fast heating of the sheet metal. Conductive heating presents a number of advantages over the in-furnace heating method. These include a more efficient use of energy, as well as the requirement of less time and space for heating, thus lowering costs. After press-hardening was performed using both methods, the microstructural and mechanical characterizations of both specimens were examined for optical microscopy, hardness, tensile strength, and high-speed impact tests. The results showed that the press-hardening process transformed the ferritic–pearlitic microstructure in the as-received state into martensite after die quenching and caused a substantial increase in hardness and strength at the expense of ductility and impact toughness. On the other hand, no significant difference was observed in either the microstructure or mechanical properties with respect to the heating method used. The results obtained in the present investigation concur with the findings of current literature.

Effect of olive pulp enrichment on physicochemical and antioxidant properties of wheat bread

Black and green olive pulp was added to wheat bread formulation at different levels (5, 10, 15%) with the aim to improve its nutritional value by enhancing the phenolic content and antioxidant capacity. Additionally, the effects of the fortification with olive pulp on the physical characteristics, staling rate and overall consumer acceptability of the formulated breads were explored. Both olive pulps exhibited significantly higher antioxidant activity than refined wheat flour. Baking imparted an impressive increase in TPC, TFC and antioxidant activity of breads as revealed by comparison of experimental with theoretical values but returned significant differences only in the case of TPC when a two-tailed t-test for paired data was applied. Texture measurements showed a substantial increase in hardness with storage along with decreasing loaf volume and increased density. Hydroxytyrosol was the major phenolic compound of fortified breads followed by tyrosol. Olive pulp could be incorporated in a bread formulation without interfering with the general sensory acceptability.

The effect of ionic liquid and superbase pre-treatment on the spring-back, set-recovery and Brinell hardness of surface-densified Scots pine

Abstract Compressing the surface of sawn timber results in a substantial increase in hardness, and this opens up new market opportunities of using low-density timber species as the raw material for high-value wood products. Unfortunately, widespread commercialisation is hindered by the lack of an industrially viable surface densification process, the major obstacle being the set-recovery (SR) of the densified wood cells upon exposure to moisture. Our hypothesis is that partial dissolution of the crystalline cellulose during densification will largely prevent the SR of densified wood. We therefore evaluated the effect of ionic liquid (IL) or organic superbase pre-treatment on the elastic spring-back (SB), SR and Brinell hardness (HB) of surface-densified wood. Specimens of Scots pine were treated with solutions of ILs or superbases, and then densified in a hot press at temperatures between 200°C and 270°C. The SR was reduced from 90% for the control group to only about 10% for the treated materials. The treated and densified specimens exhibited a higher HB than their untreated and densified counterparts. The method presented in this study is a precursor to the development of a continuous densification process adapted for an open system. Further studies are needed to understand the underlying mechanisms of the pre-treatment.

Evolution of the microstructural and mechanical properties of BAM-11 bulk metallic glass during ion irradiation and annealing

Ion irradiation and annealing experiments were performed on Zr52.5Cu17.9Ni14.6Al10Ti5 “BAM-11” bulk metallic glass (BMG) specimens to evaluate their irradiation- and temperature-induced microstructural and mechanical property evolution. For the ion irradiations, samples were exposed to 9 MeV Ni3+ ions to a midrange (∼1.5 nm depth) dose of 10 displacements per atom (dpa) at temperatures ranging from 25 to 360 °C. A separate set of samples were annealed at 150 °C, 200 °C and 300 °C with respective heating times of 96, 72, and 48 h. Bulk X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterization revealed that the alloy did not crystallize during irradiation up to 290 °C, although partial crystallization occurred at 360 °C throughout the unirradiated and irradiated regions of the sample. Transmission electron microscopy (TEM) characterization suggested that some of the irradiated region retained an amorphous structure, supporting the idea of partial crystallization. XRD analysis revealed that the crystallization which occurred in the sample irradiated at 360 °C was caused by thermal effects, and not irradiation displacement damage, and may be due to slight impurity contamination in the ingot. Nanoindentation experiments showed that only a slight amount of hardening was observed in the specimen irradiated at room temperature and 290 °C. However, significant hardening occurred in the sample irradiated at 360 °C (∼18% increase) as well as the unirradiated annealed specimens. For the sample irradiated at the highest temperature, the substantial increase in hardness was attributed to the partial crystallization of the alloy due to thermal, rather than irradiation effects. Overall, the results of the XRD and nanoindentation characterizations indicate good stability during irradiation at 25–290 °C but suggest that the BAM-11 BMG is not suitable for irradiation environments where temperatures exceed 300 °C for prolonged periods of time. Three different extrapolation models were employed to study how irradiation and annealing modify the indentation size effect (ISE) in the BAM-11 BMG. The poor linear fitting, as exhibited by all of the underlying equations, indicate that a new ISE model is needed to quantify nanoindentation mechanical properties in BMGs.

The influence of mechanical activation process on the microstructure and mechanical properties of bulk Ti2AlN MAX phase obtained by reactive hot pressing

Abstract The effect of mechanical activation process on the microstructure and mechanical properties of bulk nanostructured Ti2AlN compound has been investigated in this work. The mixture of Ti and AlN powders was prepared in a 2:1 molar ratio, and a part of this powder was subjected to a high-energy milling process under argon atmosphere for 10 h using agate as grinding media. Finally, the densification and formation of the ternary Ti2AlN MAX phase through solid state reaction of both unmilled and milled powders were carried out by hot pressing under 15 or 30 MPa at 1200 °C for 2 h. The microstructure of precursor powder mixtures and the consolidated samples was characterized by using X-ray diffraction (XRD) and a scanning electron microscope equipped with an energy dispersive X-ray spectroscopy (SEM/EDS). The X-ray diffraction patterns were fitted using the Rietveld refinement for phase quantification and to determine their most important microstructural parameters. Microstructure and mechanical properties of the consolidated samples were correlated with the load used for the hot pressing process. The substantial increase of hardness, the higher densification and the lower grain sizes observed in the samples prepared from the activated powders were attributed to the formation of second phases like Ti5Si3 and Al2O3.

Relationship between the microstructure and properties of thermomechanically processed Fe−17Mn and Fe−17Mn−3Al steels

Two austenitic Mn steels (Fe−17Mn and Fe−17Mn−3Al (wt%, so as the follows)) were subjected to thermomechanical processing (TMP) consisting of forging followed by solutionization and hot rolling. The rolled samples were annealed at 650 and 800°C to relieve the internal stress and to induce recrystallization. The application of TMP and heat treatment to the Fe−17Mn/Fe−17Mn−3Al steels refined the austenite grain size from 169 μm in the as-solutionized state to 9–13 μm, resulting in a substantial increase in hardness from HV 213 to HV 410 for the Fe−17Mn steel and from HV 210 to HV 387 for the Fe−17Mn−3Al steel. The elastic modulus values, as evaluated by the nanoindentation technique, increased from (175 ± 11) to (220 ± 12) GPa and from (163 ± 15) to (205 ± 13) GPa for the Fe−17Mn and Fe−17Mn−3Al steels, respectively. The impact energy of the thermomechanically processed austenitic Mn steels was lower than that of the steels in their as-solutionized state. The addition of Al to the Fe−17Mn steel decreased the hardness and elastic modulus but increased the impact energy.

Low friction and high strength of 316L stainless steel tubing for biomedical applications

We propose herein a nondestructive surface modification technique called ultrasonic nanocrystalline surface modification (UNSM) to increase the strength and to improve the tribological performance of 316L stainless steel (SS) tubing. Nanocrystallization along nearly the complete tube thickness of 200μm was achieved by UNSM technique that was confirmed by electron backscatter diffraction (EBSD). Nano-hardness of the untreated and UNSM-treated specimens was measured using a nanoindentation. Results revealed that a substantial increase in hardness was obtained for the UNSM-treated specimen that may be attributed to the nanocrystallization and refined grains. Stress-strain behavior of the untreated and UNSM-treated specimens was assessed by a 3-point bending test. It was found that the UNSM-treated specimen exhibited a much higher strength than that of the untreated specimen. In addition, the tribological behavior of the untreated and UNSM-treated specimens with an outer diameter (OD) of 1.6mm and an inner diameter (ID) of 1.2mm was investigated using a cylinder-on-cylinder (crossed tubes of equal radius) tribo-tester against itself under dry conditions at ambient temperature. The friction coefficient and wear resistance of the UNSM-treated specimen were remarkably improved compared to that of the untreated specimen. The significant increase in hardness after UNSM treatment is responsible for the improved friction coefficient and wear resistance of the tubing. Thus, the UNSM technique was found to be beneficial to improving the mechanical and tribological properties of 316L SS tubing for various potential biomedical applications, in particular for coronary artery stents.

Mechanism of hot-rolling crack formation in lean duplex stainless steel 2101

The thermoplasticity of duplex stainless steel 2205 (DSS2205) is better than that of lean duplex steel 2101 (LDX2101), which undergoes severe cracking during hot rolling. The microstructure, microhardness, phase ratio, and recrystallization dependence of the deformation compatibility of LDX2101 and DSS2205 were investigated using optical microscopy (OM), electron backscatter diffraction (EBSD), Thermo-Calc software, and transmission electron microscopy (TEM). The results showed that the phase-ratio transformations of LDX2101 and DSS2205 were almost equal under the condition of increasing solution temperature. Thus, the phase transformation was not the main cause for the hot plasticity difference of these two steels. The grain size of LDX2101 was substantially greater than that of DSS2205, and the microhardness difference of LDX2101 was larger than that of DSS2205. This difference hinders the transfer of strain from ferrite to austenite. In the rolling process, the ferrite grains of LDX2101 underwent continuous softening and were substantially refined. However, although little recrystallization occurred at the boundaries of austenite, serious deformation accumulated in the interior of austenite, leading to a substantial increase in hardness. The main cause of crack formation is the microhardness difference between ferrite and austenite.

Effect of Strontium and Misch Metal on Al–14Si–3Mg Alloy

The individual and combined effect of Strontium and Misch metal on microstructure and properties of Al–14Si–3Mg alloy was investigated. Addition of 3 wt% Mg to Al–14Si alloy resulted in microstructure comprising of α-Al and ternary eutectic (α-Al, Si and Mg2Si). It was found that Strontium and Misch metal behaved differently when added to Al–14Si–3Mg alloy resulting in significantly different microstructure. While addition of only strontium did not show formation of any new phase having any deleterious effect on microstructure and hardness, the addition of only misch metal though, led to the appearance of rare earth rich phases with branched morphology resulting in decrease in hardness. Also, it was concluded that misch metal in conjunction with strontium yielded best results in terms of microstructure and hardness. The microhardness measurements showed that ternary eutectic region was 1.4–1.7 times harder than the binary eutectic region. Furthermore, the T6 treated Al–14Si–3Mg alloy containing Strontium and Misch metal led to a substantial increase in hardness which was superior to some commercially available Al–Si alloys. Also, differential scanning calorimetry studies were carried out to determine the freezing range of the alloys and assess their feasibility for semisolid processing.

Wear behavior of copper-containing ferritic iron under a dry sliding condition

The effect of solute Cu and Cu precipitates on the wear behavior of ferritic iron under an unlubricated condition was investigated. The specific wear rate of Cu-containing steel abruptly decreased up to 50 N of load, and then gradually decreased with further increased load. The specific wear rate of the as-quenched specimen, in which Cu was in a solid solution, was the lowest among all the specimens at low loads, and all specimens had almost the same specific wear rate at high loads. Subsurface observation showed that the hardness increments of all specimens decreased with increased depth below the worn surface. The as-quenched specimen had a relatively large depth of deformed region than the other specimens even though the increments in hardness were almost the same for all specimens at low loads. With the same hardness at an unworn state, the as-quenched and over-aged specimens exhibited a substantial increase in hardness and large deformed regions below the worn surfaces. This finding indicated that the enhancement in plastic deformation and work hardening led to the decrease in the specific wear rate of the as-quenched specimen at low loads and the improvement in the wear resistance of all specimens at high loads.

Structure and Properties of Nano-Scale Oxide-Dispersed Iron

Bulk samples of pure iron and yttria dispersed iron with and without titanium (i.e., Fe, Fe-Y2O3, and Fe-Y2O3-Ti) were prepared by hot extrusion of high-energy ball-milled powders. An examination of the microstructure using TEM revealed that the addition of titanium resulted in the reduction of the dispersoid size with a concomitant increase in the volume fraction of the dispersoids. As a result, Fe-Y2O3-Ti exhibited a substantial increase in hardness and tensile properties as compared to Fe and Fe-Y2O3. The higher hardness and strength of Fe-Y2O3-Ti is shown to be due to the presence of finer and higher number density of Y-Ti-O complex oxides. Dynamic strain aging in the temperature range of 423 K to 573 K (150 °C to 300 °C) was observed in all the compositions studied.