Uniform Grain Size Research Articles

Effects of Li concentration in the precursor solution on NiO thin films deposited using electrostatic spray deposition

Abstract Undoped and Li-added NiO thin films were deposited using electrostatic spray deposition (ESD) techniques. Initially, the NiO thin films displayed minimal contamination, predominantly C and H. The NiO thin films exhibited a flat surface morphology comprising grains of uniform size, approximately 20–30 nm in diameter, and reliable crystal growth, with a full width at half maximum of approximately 0.30 in X-ray diffraction analysis. Moreover, the NiO/ZnO diode demonstrated superior properties when a 5 at. % Li concentration solution was incorporated. The rectification ratio reached approximately 2.3 × 10³ at ± 1.0 V, with an ideality factor of 1.9. Additionally, the NiO/ZnO diodes exhibited remarkable photovoltaic properties even without detailed optimization. These findings underscore the potential of ESD in advancing semiconductor thin-film technology, thereby paving the way for more cost-effective and scalable production methods.

Effects of Length-to-Width Ratio on Magnetic and Microstructural Properties of Die-Upset Nd-Fe-B Magnets.

In this study, the effects of the length-to-width ratio on the magnetic and microstructural properties of die-upset Nd-Fe-B magnets were examined. A die-upset magnet with a uniform shape and no significant cracking was successfully developed. During the die-upset process, the applied pressure was not uniform across the magnet and varied depending on its shape and position. In the case of the magnet with a 4:1 ratio, which had the largest length-to-width ratio, there was a higher concentration of stress at the edges compared to the center, resulting in easier grain deformation and growth at the edges, which led to the lowest remanence and (BH)max. As the length-to-width ratio approached 1:1, the grain size increased slightly, reducing the coercivity; however, the magnets maintained a uniform grain-size distribution. The change from a rectangular to a square pressing surface resulted in a more uniform stress distribution, particularly at the center and corners, which improved the consistency of the magnetic properties across different regions of the magnet. Consequently, an 11.9% enhancement in (BH)max, reaching 285.6 kJ/m3, was achieved in the 1:1 ratio die-upset magnet, which is attributed to the uniform grain size and improved grain alignment.

Regulating hardness homogeneity and corrosion resistance of Al-Zn-Mg-Cu alloy via ECAP combined with inter-pass aging

The novel processing strategies of Equal Channel Angular Pressing (ECAP) combined with inter-pass aging was designed, and XRD, SEM, TEM, electrochemical testing, and hardness testing were used to evaluate the relationship between microstructure and performance of alloys in this work. The results indicate that the hardness uniformity of the circular cross-section perpendicular to the extrusion direction was improved by combining ECAP with inter-pass aging, resulting in a hardness inhomogeneity factor (∼0.030) that was lower than that achieved by peak aging and double-stage aging alloys. Polarization curves and electrochemical impedance spectra show that a more negative corrosion potential and a smaller corrosion current density were possessed by the alloy, with the maximum intergranular corrosion depth (IGC) being reduced to 38 μm. Microstructure observation indicates that the improvement in hardness uniformity is due to the uniformity of grain size and the improved distribution and size of the η’ phase, which is attributed to the interaction between the pinning and shear effects of precipitates and dislocations during deformation. The enhanced corrosion resistance was attributed to an orderly combination of deformation and aging that increases the grain boundary volume and disrupts the η phase continuity within grain boundaries.

Influence of hot forging on grain formation in Al0.35CoCrFeNi high-entropy alloy: numerical simulation, microstructure and mechanical properties

One-step (F100) and three-step (F30-60-40) hot forging of Al0.35CoCrFeNi alloy was investigated to achieve a uniform equiaxed grain structure. In the as-cast and forged state, only a single-phase face-centered cubic structure was observed. The formation of twins, recrystallized and partially recrystallized grains in the volume of the samples was observed depending on used forging process. To predict uniform grain-size formation numerical simulation of the hot-forging process was used. The numerical model was calibrated and validated by means of measured compression experimental data of as-cast Al0.35CoCrFeNi alloy before forging. Thermal analysis using finite element analysis was used to simulate cooling of sample during the relocation from the furnace on the lower die. Simulations were run under different thermo-mechanical conditions and the regions for the formation of dynamically recrystallized grains were predicted. Room temperature mechanical properties were evaluated after F100 and F30-60-40 hot-forging process. The F30-60-40 hot forging optimized the grain size, which was evident in the very small dispersion of the room temperature mechanical properties in tension. Elongation after F30-60-40 hot forging increased by 17%. The correlation between temperature, equivalent stress, equivalent plastic strain, microstructure, tensile properties, and strain-hardening behavior is discussed.

Physical Properties Studies of Magnesium Phthalocyanine (MgPc) Thin Films of Different Annealing Temperatures Prepared by Pulsed Laser Deposition Technique

Magnesium Phthalocyanine (MgPc) was deposited on a glass substrate by pulsed laser deposition (PLD) using Q-Switching Nd:YAG laser with wavelength 1064 nm, repetition rate 6 Hz, at room temperature (300K) and different annealing temperatures (373, 473, and 573)K under vacuum condition of 10-3 torr. All films were annealed for one hour to attain crystallinity. X-ray diffraction (XRD) of MgPc powder indicated that MgPc crystallizes in polycrystalline with a monoclinic structure. While comparing the MgPc films, it was observed that the intensity of the characteristic peak increases with temperature, and the crystallization exhibited a monoclinic structure typical of the β-form. The Miller indices, hkl, values for each diffraction peak in the XRD spectrum were calculated. The characteristic peak of Phthalocyanine (MgPc) was found at 2θ value 6.9137ᵒ with the hkl value of (100) for both MgPc powder and deposited thin films. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX) analyses indicated that crystallinity improved and surface morphology was enhanced with the rise in annealing temperature and showed uniform-sized grains. They also assisted in identifying the optimal parameters that yielded the best structural properties for the film. The optical properties of MgPc thin film showed two absorption bands. The MgPc thin films exhibit transport and onset direct energy gaps (Eg) for all samples. Additionally, the absorption coefficient (α) was calculated using Lambert Law, revealing a slight dependence on the annealing temperature.

Effect of rare earth element Y addition on the corrosion resistance of Cu-12.5Ni-5Sn alloy after aging

Cu-12.5Ni-5Sn-xY alloy with different rare earth Y contents was prepared by spark plasma sintering (SPS). The samples underwent aging at approximately 400°C for 4 hours in an energy-saving box furnace. The effect of trace Y addition on the microstructure and corrosion behavior of aging treated Cu-12.5Ni-5Sn-xY alloy were investigated by electrochemical test, and the corrosion mechanism of the alloy was discussed. The results indicated that the addition of rare earth Y improved the uniformity of microstructure and grain size of the alloy, and improved the corrosion resistance of the alloy. When the Y content changed between 0 wt% and 1.0 wt%, the corrosion resistance of the Cu-12.5Ni-5Sn-xY alloy gradually improved. The Cu-12.5Ni-5Sn-1.0Y alloy had a lower self-corrosion current density (1.490×10−5A/cm2) and a lower corrosion rate (0.178 mm/a). Compared to the Cu-12.5Ni-5Sn alloy without Y addition, the maximum corrosion depth was reduced by about 44.6 % and the corrosion resistance was improved. Rare earth Y promoted the uniform distribution of Ni elements, inhibited the conversion of Cu2O to Cu2(OH)3Cl, enhanced the layer density and stability. The internal corrosion layer mainly consisted of NiO, the intermediate layer mainly consisted of SnO, and the surface layer mainly comprised of CuO, Cu2O, and Cu2(OH)3Cl. Additionally, Y2O3 formed on the alloy's surface, effectively prevented corrosive ion attack and enhanced the corrosion resistance of Cu-12.5Ni-5Sn alloy.

Figures of merit of PLZT ferroelectric ceramics for practical applications

Structural, microstructural and pyroelectric properties were investigated in PZT-based ferroelectric ceramics for a composition close to the morphotropic phase boundary (Zr/Ti = 53/47), as a function of the lanthanum content. The samples were prepared via the conventional solid-state reaction sintering method. Three compositions were synthetized and studied following the PbZr0.53Ti0.47O3 + x mole% La nominal formula, where x = 0.0, 2.5 and 5.0. The structural characterization confirmed the presence of both tetragonal and rhombohedral phases for all the studied compositions, showing a decrease in the tetragonality factor (c/a) with the increase of the lanthanum concentration. The observed decrease in the stability of the ferroelectric phase (in favor of the paraelectric one) have been discussed in light of the solubility of the doping cation into the studied PZT perovskite structure. Microstructural properties revealed low pores concentration micrographs, showing homogeneous microstructures and uniform grain-sizes. The pyroelectric response of the as-prepared PLZT samples was also investigated in a wide temperature interval. The lower lanthanum content composition exhibited the best properties, characterized by a high pyroelectric coefficient and enhanced figures of merit. These characteristics make such a composition a promising material for practical applications.

Determination of the supramolecular arrangement of Dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene films fabricated by Physical Vapor Deposition and possible implications for electronic devices

Organic thin films have been used as active layers and are an alternative to inorganic materials in order to improve the performance of electronic devices. Recently, Dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) became an important compound in organic electronics due to its optical and electrical properties, which are dependent on the supramolecular arrangement. Thus, in this work we determined the supramolecular arrangement of organic thin films of DNTT (DNTT PVD films) fabricated by Physical Vapor Deposition (PVD). Ultraviolet-visible absorption spectra showed the controlled growth of the films within the range from 17 to 120 nm and the formation of aggregates (J- and H-), as the H-aggregate was favored by the thickness. The emission spectra revealed that excimers are responsible for the emission in DNTT PVD films and the increase in solution concentration led to the formation of H-aggregates primarily. The molecular organization of the films, determined by selection rules of Fourier Transform Infrared absorption spectroscopy, suggested that the molecules had a preferential chain-on organization for 120 nm thickness film. Complementary, X-Ray Diffraction data showed that DNTT PVD film was practically monocrystalline with monoclinic cell unit, also determined for the 120 nm thickness film. Atomic Force Microscopy measurements revealed that DNTT film had a homogeneous surface (roughness around 6 nm for the film with 120 nm thickness) with grains of uniform size and geometry. Thus, based on the characteristics of the supramolecular arrangement (especially the molecular organization and increase of H-aggregates with the thickness of DNTT PVD film and the results found in the literature), it was possible to analyze probable implications of chain-on molecular organization and the increase of H-aggregates with the film thickness on the mobility of charge carriers of devices, such as diodes and transistors, in which they are applied.

Structural and electrical studies of B3+-and-In3+-ion co-doped Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes

In this study, B3+ and In3+ ions were co-doped at the Al3+ sites of Li1.3Al0.3Ti1.7(PO4)3 electrolyte using a solid-state reaction with the goal of obtaining electrolytes with remarkable Li-ion conductivities. B3+-ion doping enhanced the densification of Li1.3Al0.3-yByTi1.7(PO4)3 electrolytes, and Li1.3Al0.22B0.08Ti1.7(PO4)3 electrolyte delivered the highest relative density of 97.6%. Subsequent In3+-ion doping further enhanced densification, and Li1.3Al0.21B0.08In0.01Ti1.7(PO4)3 electrolyte delivered the highest relative density of 98.2%. However, the electrolyte densification diminished rapidly upon further increasing the In3+-ion content. The peaks in the X-ray diffraction patterns of the Li1.3Al0.3-yByTi1.7(PO4)3 and Li1.3Al0.22-xB0.08InxTi1.7(PO4)3 electrolytes were indexed to rhombohedral NASICON-type LiTi2(PO4)3 with the space group R3¯c with trace amounts of LiTiPO5 secondary phase. Upon incorporating In3+ ions into the lattice of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte, the cell volume and the transport channels for Li+ ions were expanded, while B3+-ion incorporation slightly contracted the cell. The scanning electron microscopy and Raman spectroscopy results indicated that B3+-ion substitution into the Li1.3Al0.3Ti1.7(PO4)3 lattice to obtain Li1.3Al0.3-yByTi1.7(PO4)3 electrolytes, which led to the increase in the structural order of the lattices and promoted the formation of microstructures with superior crystallinity and smaller and more uniform grain sizes. Further, B3+ and In3+-ions co-doped Li1.3Al0.22-xB0.08InxTi1.7(PO4)3 electrolytes showed lower structural order, larger grain size, lower grain-size uniformity, and more pore contents than those of undoped Li1.3Al0.3Ti1.7(PO4). The ionic conductivities of the Li1.3Al0.3-yByTi1.7(PO4)3 electrolytes increased with increasing concentration of B3+-ion dopant and reached a maximum of 8.35× 10−4 S/cm for Li1.3Al0.22B0.08Ti1.7(PO4)3. Among the Li1.3Al0.22-xB0.08InxTi1.7(PO4)3 electrolytes, Li1.3Al0.21B0.08In0.01Ti1.7(PO4)3 presented the highest ionic conductivity of 1.08 × 10−3 S/cm, which was closely correlated to its high relative density. The contribution of electronic conductivity to total conductivity was found to be trivial.

Brazing manufacturing technology of plate-fin heat exchanger for solid oxide fuel cells

The plate-fin heat exchanger (PFHE) is the core equipment used to achieve the high efficiency of solid oxide fuel cell (SOFC), however, the issues of high-performance brazed joints in the manufacturing of the PFHE have been a challenge due to the poor mechanical properties. This study proposes a brazing manufacturing technology of isothermal solidification with the optimized post bonding heat treatment strategy, to synergistically improve the strength-ductility property and homogenize microstructure of brazed joints, aiming at guaranteeing the high energy efficiency of SOFC. The results show that brazing at 1065 °C for 25 min achieves the complete isothermal solidification and an intermetallic-free joint centerline with numerous borides generating in the diffusion-affected zone. Solution treatment then dissolves large quantities of acicular and blocky borides. The uniformity of grain size and kernel average misorientation distribution is also improved due to recrystallization, which becomes more pronounced after solution aging treatment. In addition, solution aging treatment results in an improvement in the ultimate tensile strength of the brazed joint, which is more prominent than that after solution treatment. However, the increase in elongation after solution aging treatment is smaller than after solution treatment, while still much higher than the as-brazed joint due to the dissolution of boride precipitates and growth of twin boundaries. The results demonstrate that the proposed brazing manufacturing technology not only homogenizes microstructure, but also significantly improves strength and ductility, further promoting the long-life operation of SOFC.

Tailoring of the microstructure and mechanical properties of the flow formed aluminum alloy sheet

Tube flow forming followed by flattening is an effective way to make ultra-wide sheet for plastic forming of large thin-walled components. However, the work hardening and poor plasticity of flow formed sheet seriously restrict the subsequent plastic formability. To tailor the plastic formability, two types of heat treatments (recrystallization annealing and solution quenching) were conducted on the flow formed 2219 aluminum alloy sheet, and their microstructure evolution and mechanical properties were comparatively studied to obtain a suitable heat treatment scheme. It is found that the deformation in flow forming produces quantities of deformed substructures and the rotating cubic texture. In the recrystallization annealing, recrystallization occurs with the co-existence of two nucleation mechanisms, i.e., subgrain nucleation and particle stimulated nucleation, which produce a weak {100}//RD-CD texture and higher plasticity than that of the flow formed sheet. In addition, it is found that the annealing temperature and holding time have complex interactive effects on the average grain size, the uniformity of grain size and the resultant plasticity. In contrast, the solution quenching obtains weak {100}∥RD-CD texture at lower solution temperature and cube texture at higher solution temperature, respectively; meanwhile, it produces larger average grain size and better grain size uniformity than the recrystallization annealing. Because the uniform grain size can suppress the heterogeneous deformation and the dissolution of second phase particles can delay the generation of crack, the solution quenched sheet presents better plasticity than the recrystallization annealed sheet. Moreover, increasing the solution temperature can improve the plasticity. Therefore, it is suggested to take a solution quenching scheme with higher temperature (535 °C for 30 min) to tailor the flow formed sheet, which can get a similar elongation as that of the initial tube blank.

Importance of uniformity of grain size to reduce dc degradation and improve reliability of ultra-thin BaTiO3-based MLCCs

Excellent direct current (dc)-bias and reliability have become increasingly important for ultra-thin BaTiO3-based multilayer ceramic capacitors (MLCCs). Herein, X5R-MLCCs with a thickness of ∼1 μm are fabricated using BaTiO3 with varied grain size. It is shown that the uniformity of the grain size plays an important impact on the direct current (dc)-bias and the reliability of ultra-thin MLCCs. Uniform grain size, which is indicative of good distribution of doping element contributes to improved temperature stability. By contrast, abnormal large grains induce reinforced space charge polarization. Chips with non-uniform grains exhibit dramatic dielectric constant change under dc-bias due to the high tetragonality and irreversible domain-wall motion. Weibull distribution and highly accelerated life test (HALT) reveal that non-uniform grains contain more oxygen vacancies supported by impedance spectra analysis at 300–450 °C. This study provides a feasible strategy to improve the dc-bias and the reliability of the ultra-thin MLCCs.

Oriented preparation of Large-Area uniform Cs2TeI6 perovskite film for high performance X-ray detector

Large-area flexible perovskite films are attracting widespread research interest for applications in wearable solar cells, portable photodetectors, bendable X-ray imaging detectors and other implantable optoelectronic devices. In this work, a facile mobile platform assisted electrospray method is developed to prepare large-area (100 cm2) lead-free Cs2TeI6 film on flexible polyimide substrate. The spraying parameters are coupled with the growth temperature to achieve a dynamic balance. The as-prepared film by optimized process shows high uniformity in grain size, thickness and X-ray response without pinholes and cracks. Moreover, oriented nucleation is more likely to occur on the flexible organic substrates for less growth stress and mismatch stress, leading to preferred (222) plane orientation. X-ray detectors prepared with the films exhibit a resistivity of 1.9 × 1011 Ω·cm, an X-ray sensitivity of 226.8 μC⋅Gyair-1⋅cm−2 and a transient response rise time as fast as 42 ms under 50 kV X-ray at an electrical field of 6.67 × 103 V·mm−1. The modified electrospray method shows great potential applications for large-area devices of radiography, solar cell and other optoelectronic devices.

Voronoi-Based Discrete Element Analyses to Assess the Influence of the Grain Size and Its Uniformity on the Apparent Fracture Toughness of Notched Rock Specimens

The fracture toughness reflects the rock resistance to crack propagation, and therefore represents an important parameter for rock fracture assessments. From a strict point of view, the real fracture toughness (it {K}_{mathrm{it IC}}) corresponds to a cracked situation in which the notch radius is theoretically equal to zero. However, most of the defects in rocks have a finite radius and, therefore, should be studied as notch-type defects. Here, the notch effect is numerically studied together with the influence of the grain size and the sorting coefficient (grain size uniformity) on the apparent fracture toughness (it {K}_{mathrm{it IN}}). To this end, several four-point bending tests with different U-shaped notch radii, mean grain sizes and degrees of uniformity in grain size and shape have been simulated using the Discrete Element Method. In order to represent the grains of the rocks, the Voronoi tessellation is used to create randomly sized and distributed polygonal blocks. These Voronoi polygons have been defined, on the one hand, by an average edge length of 1, 2 and 3 mm, and, on the other hand, by a different number of iterations (n) in the relaxation process during the generation of the polygons, which defines the grain size uniformity. The numerical analyses performed and the interpretation of the results show a clear notch effect in all the studied cases, as the apparent fracture toughness (it {K}_{mathrm{it IN}}) increases with notch radius. Finally, the obtained stress fields at the notch tip have been compared to those obtained from the traditional finite element method.

Effect of annealing on microstructure evolution and age-hardening behavior of dilute Mg–Al–Ca–Mn alloy

Microstructure evolution and mechanical properties of the as-drawn dilute Mg-0.8Al-0.1Ca-0.6Mn (wt. %) alloy wires during annealing and peak-aging treatment were investigated in this paper. The results show that the high density of nano-sized Al–Mn precipitates strongly hindered grain boundary migration to restrict grain growth during annealing under 300 °C and 400 °C, while grain growth was obvious and the uniformity of recrystallization grain size increased due to partial dissolution of Al–Mn precipitates at 500 °C. In addition, there was a growth preference in grains with (0001) <2 1¯1¯ 0> orientation, which was closely associated with the texture changes. The alloy annealed at 500 °C for 10min exhibits remarkable age-hardening response and both the tensile yield strength and elongation to failure were improved simultaneously after peak-aging treatment, which was mainly attributed to the monolayered Guinier-Preston (G.P.) zones and planar Al2Ca precipitates.

Effect of conventional and microwave sintering on microstructure and ferroelectric properties of sodium bismuth titanate (NBT) perovskite ceramics

Microstructure and ferroelectric properties of Na0.5Bi0.5TiO3 ceramic prepared by SSR method with different sintering route were investigated to study the effect of microwave sintering on the energy storage properties. Rietveld refinement of XRD data showed trigonal (Rhombohedral) single phase structure with R3C space group and SEM micrographs showed the dense microstructure with little surface segregation and most uniform grainsize distribution found for 10 min. microwave sintering. The slim shape P-E loop confirms low energy losses in all studied samples. Microwave sintering found useful to improve ferroelectric properties of studied samples and good optimization of ferroelectric parameters achieved for 10 min. microwave sintering in present studied system.

Effect of energy on Ti plate fabrication by vacuum selective laser melting for uniformity of grain size

Grain size homogenization by controlling heat input using modulated pulses in additive manufacturing was verified. A Ti plate was fabricated with a modulated pulsed laser by vacuum selective laser melting. 20-layer fabrication was performed with modulated pulsed laser and continuous wave laser. As a result of cross-sectional observation, it was found that the variation of the grain size was smaller when the modulated pulsed laser was used. These experimental results suggest that it is possible to control the grain size by using a modulated pulsed laser.

Effect of the Initial Columnar‐Grained Inhomogeneity of Electrical Steels on the Transformation Temperature

The effects of various initial structures and heating and cooling rates on the columnar‐grained transformation temperature are studied by a thermal dilatometer and electron backscatter diffraction. The results show that deformation can reduce the thermal hysteresis more effectively than decrease the heating rate, and the phase transformation hysteresis of the deformed sample is the smallest during heating, followed by the columnar‐grained sample with a slow heating rate, whereas the columnar‐grained sample with a fast heating rate has the largest phase transformation hysteresis. Moreover, the dilatational amount changes greatly with cooling rate. The coarse columnar grains can severely restrain dilatation. The smaller dilatational amount is related to the incomplete phase transformation of the columnar grains and also related to the suppression of the dilatational amount of the small grains by the surrounding columnar grains. In contrast, the largest dilatational amount is caused by the relatively sufficient phase transformation. In addition, the changes of the transformation temperature and the dilatational amount are mainly induced by the grain size effect and the inhomogeneity of the structures, but {100} texture can affect the uniformity of grain size.

Cm2-Scale Synthesis of MoTe2 Thin Films with Large Grains and Layer Control.

Owing to the small energy differences between its polymorphs, MoTe2 can access a full spectrum of electronic states from the 2H semiconducting state to the 1T' semimetallic state and from the Td Weyl semimetallic state to the superconducting state in the 1T' and Td phase at low temperature. Thus, it is a model system for phase transformation studies as well as quantum phenomena such as the quantum spin Hall effect and topological superconductivity. Careful studies of MoTe2 and its potential applications require large-area MoTe2 thin films with high crystallinity and thickness control. Here, we present cm2-scale synthesis of 2H-MoTe2 thin films with layer control and large grains that span several microns. Layer control is achieved by controlling the initial thickness of the precursor MoOx thin films, which are deposited on sapphire substrates by atomic layer deposition and subsequently tellurized. Despite the van der Waals epitaxy, the precursor-substrate interface is found to critically determine the uniformity in thickness and grain size of the resulting MoTe2 films: MoTe2 grown on sapphire show uniform films while MoTe2 grown on amorphous SiO2 substrates form islands. This synthesis strategy decouples the layer control from the variabilities of growth conditions for robust growth results and is applicable to growing other transition-metal dichalcogenides with layer control.

The effect of phase stability on the grain growth behavior of beta titanium alloys

The grain growth kinetics of two beta titanium alloys, Ti–4733 and Ti–5553 was studied over a temperature range of 850 °C–1000 °C. The more stable alloy i.e. Ti–4733, showed a smaller average grain size and slower growth rate compared to Ti–5553 at a same annealing condition. The results showed that the uniformity of grain size decreased initially dawn to a minimum and then increased with increasing temperature. The grain growth exponent (n) and activation energy (Q) were calculated and it was revealed that n is mainly affected by temperature and Q is generally influenced by time. The n value for Ti–4733 was found to be lower than that for Ti–5553 while a higher Q was calculated for Ti–4733. The lower n values and the higher Q were attributed to the solute drag effect and the high Mo content with low diffusivity in Ti matrix.