Recrystallization Temperature Research Articles

Effect of recrystallization annealing on microstructure and properties of cold-deformed CoCrCu1.2FeNi high entropy alloy

In this paper, CoCrCu1.2FeNi high entropy alloy (HEA) was prepared by vacuum suspension melting. After 50 % cold-deformation, recrystallization annealing experiments involving the annealing temperatures of 650–950 ℃ and the annealing times of 30–120 min were carried out on the cold-deformed HEA. The microstructure and properties of the alloy were compared before and after annealing. The results showed that with the extension of annealing time and temperature, the microstructure of the alloy was gradually uniform and coarsening occurred after spheroidization. In addition, fusion and engulfment occurred in the microstructure and the microstructure size decreased first and then increased. Both the fracture strength and fracture strain of the alloy increased first and then decreased. The alloy had the best compression performance at 850 ℃/60 min. Compared with the alloy after cold-deformation, the fracture strength was increased by 79.3 %, the fracture strain was increased by more than 1 time, and the comprehensive mechanical properties were the best at 750–850 ℃. The average hardness decreased with the increase of temperature and annealing time, and the initial recrystallization temperature of the alloy was determined to be about 650 ℃. The formation of annealing twins refined the microstructure and improved the properties of the alloy.

Unveiling the optimal selenization temperature for enhancing efficiency in flexible Cu(In,Ga)Se2 thin film solar cells

This work is centered on the growth of metallic precursors (Cu/In/Ga) through sequential evaporation, followed by a controlled ramping step selenization process aimed at synthesizing thin films based on copper indium gallium diselenide (CIGSe) on stainless steel substrates. Selenization temperatures ranging from 475 to 525 °C were employed to optimize the most suitable recrystallization temperature. A comprehensive characterization was conducted, covering structural, morphological, topographical, optical, and electrical aspects, revealing the distinct role of selenization temperature. Subsequently, solar cells were fabricated using the synthesized absorbers, resulting in an impressive efficiency of 15.89 % for the absorber selenized at 525 °C. This observation underscores the pivotal role of selenization parameters in shaping the quality of CIGSe, directly influencing the performance of solar cells. Consequently, this research not only focuses on refining the growth process of CIGSe through a modified approach but also provides valuable insights for the advancement of flexible solar cell technology.

Effects of thermal ageing time and temperature during heat-treatment on the mechanical properties of fiber laser welded Nb-1%Zr-0.1%C alloy in continuous wave mode

The effects of thermal ageing time and temperature used during heat-treatment were studied on tensile strength, elongation, and microhardness of the laser welded Nb-1%Zr-0.1%C alloy in continuous wave mode. Post-weld heat treatment (PWHT) was carried out by varying the temperature and time in the ranges of (850–1050) °C (that is, about the recrystallisation temperature) and (0.5–4) h (as the weld samples were prepared in the form of sheets), respectively. The grain sizes of fusion zone (FZ), and FZ heat treated at 850 °C for 4 h and that at 950 °C for 2 h were found to be equal to 52.85 μm, 84.89 μm and 116.43 μm, respectively. The segregation of zirconium, carbon and oxygen increased grain boundary energy and induced brittleness to the grain boundary, resulting in loss of ductility. The micro-hardness and Young's modulus values were observed to increase in the FZ compared to that of the base metal (BM), but their decreasing trends were noticed during the heat-treatment due to the grains' softening. For the PWHT samples, the plasticity was found to decrease to about 57% of that of BM. This was attributed to the precipitation of carbides, grain growth, and dislocation pinning during the ageing process. During the heat-treatment of the welded samples, both Yield Strength (YS) and Ultimate Tensile Strength (UTS) were found to decrease to 77% and 86%, respectively, of that of the BM.

Recrystallization kinetics of larger yttria particle dispersion tungsten alloy warm rolled to 50% thickness reduction

Tungsten-based materials are considered one of the candidate materials for the key components (such as the first wall and diverter) of future thermonuclear fusion reactors because of their excellent properties. At high operation temperatures, restoration processes such as recovery, recrystallization and grain growth will unavoidably embrittle ductile tungsten achieved by rolling. Dispersed second-phase particles will affect the recrystallization behavior. The thermal stability of a yttria dispersion-strengthened tungsten plate warm-rolled to 50% thickness reduction is investigated. Isochronous annealing is used to predict its recrystallization temperature range and isothermal annealing is used to study its recrystallization kinetics. The tungsten alloy in the present study has a faster recrystallization kinetics and a smaller activation energy compared to that of W-2 vol% Y2O3 alloy with small Y2O3 particles, indicating that the larger Y2O3 particles have little effect on impeding grain boundaries during recrystallization.

PPB structure elimination, DRX nucleation mechanisms and grain growth behavior of the 3rd-generation PM superalloy for manufacturing aviation components

Previous Particle Boundary (PPB), as the detrimental structure in Powder Metallurgy (PM) components, should be eliminated by subsequent hot process to improve the mechanical properties. The objective is to investigate the Dynamic Recrystallization (DRX) nucleation mechanisms and grain growth behavior of the 3rd-generation PM superalloy with PPB structure. Microstructure observation reveals that PPB decorated with (Ti, Ta, Nb)C carbides belongs to the discontinuous chain-like structure. The elimination of PPB networks can be achieved effectively via hot deformation due to the occurrence of DRX. Four different DRX nucleation mechanisms were proposed and discussed in detail according to the special microstructure characteristics of the PM superalloy. Firstly, local lattice rotations can be detected in the vicinity of (Ti, Ta, Nb)C carbides during hot deformation and thus PPB structure serves as the preferential nucleation sites for DRX grains via Particle-Stimulated Nucleation (PSN). Then, Discontinuous-DRX (DDRX) characterized by grain boundary bulging dominates the microstructure refinement and Continuous-DRX (CDRX) operated by subgrain rotation can be regarded as an important assistant mechanism. At last, the initial Σ3 boundaries would lose their twin characteristics owing to the crystal rotation and then transform into the general High Angle Grain Boundaries (HAGBs). The distorted twins provide additional DRX nucleation sites, viz., twin-assisted nucleation. Particular attention was focused on the grain growth behavior of the PM superalloy in subsequent annealing process. The recrystallization temperature was determined to be about 1110 °C and 1140 °C can be considered as the critical temperature for grain growth. The findings would provide theoretical support for microstructure refinement of the 3rd-generation PM superalloy, which is of pivotal significance for improving the mechanical properties of aviation components.

Evolution of Microstructure and Texture in Grain-Oriented 6.5% Si Steel Processed by Rolling with Intrinsic Inhibitors and Additional Inhibitors.

A grain-oriented steel containing 6.5% Si, characterized by a notable Goss texture, was effectively manufactured through the rolling technique, incorporating both intrinsic inhibitors and additional inhibitors. This investigation focuses on tracking the development of texture and magnetic properties during the manufacturing process and delineates the mechanism underlying secondary recrystallization. The empirical findings clearly demonstrated the significant influence of nitriding duration and quantity on the secondary recrystallization process. In instances where additional nitrogen is absent, the intrinsic inhibitors alone do not lead to secondary recrystallization. However, when the nitriding duration is 90 s and the nitriding amount is 185 ppm, a complete secondary recrystallization structure with a strong Goss texture enables the finished products have excellent magnetic properties. The preferential growth of Goss grains is mainly governed by the enhanced mobility of high-energy (HE) grain boundaries. With the increase in annealing temperature, the occurrence of 20°-45° HE grain boundaries with Goss grains becomes more progressively frequent. At the secondary recrystallization temperature of 1000 °C, the frequency of 20°-45° HE grain boundaries with Goss grains reaches 62.7%, providing favorable conditions for the abnormal growth of Goss grains. This results in a secondary recrystallization structure predominantly characterized by a strong Goss texture. In light of these observations, the present study provides fundamental theoretical insights and serves as a valuable procedural guideline for the industrial manufacturing of 6.5% Si grain-oriented electrical steels.

Atomic Diffusion Mechanism in BF2+ Implanted and Annealed n-Fz Si junction using Analytical Approach: Comparison with 2-D TCAD Process Simulation Result

Ion implantation controls the diffusion of the dopants inside the n-Fz Si bulk of the p+n Si microstrip detector. In order to understand about the diffusion mechanism of BF2 + molecules/dopants into the n-Fz Si bulk of Double Sided Silicon Strip Detector (back side) for the R3B Silicon Tracker, it is essential to know the precise information about the microscopic defect introduces inside the Si lattice of the detector for the next phase upgrade of the R3B experiment. The purpose of this paper is to present the atomic transport and electrical activation behavior of implanted BF2+ molecules/dopants at an energy of 80 KeV and a dose of 1015 ion/cm2 into the n-Fz Double Sided Silicon Strip Detector for the R3B Silicon Tracker after annealing at 400 °C - 1350 °C.The result shows the amorphous-crystalline interface position and recrystallization temperature using the results revealed from the 2-D TCAD process simulation of the Si microstrip detector.

Comprehensive study on the through-process Goss texture evolution in Fe-3.78 wt.%Si grain oriented electrical steel

Cold rolled grain oriented steel is used in transformer cores due to its superior magnetic properties. Large Goss oriented grains develop after the final secondary recrystallization provide low hysteresis loss. The present study represents the development of Goss orientation after each processing stage of Fe-3.78 wt% Si steel with the help of electron backscatter diffraction and x-ray diffraction techniques. The Goss oriented grains developed during hot rolling and hot band annealing did not remain stable in cold rolling. On the other hand, shear bands developed inside {111}<112> component of γ-fiber texture during cold rolling. Partial recrystallization of the cold rolled sheet revealed that Goss oriented grains started evolving inside the shear bands of {111}<112> oriented grains. Intermediate annealing between cold rolling passes was found to be not essential to achieve Goss orientation in primary recrystallization. The optimum primary recrystallization temperature was in between 923 and 948 K where a significant amount of Goss oriented grains were present. Further, secondary recrystallization was attempted at different temperatures between 1173 and 1473 K. Grain boundary curvature of Goss oriented grains and all other grains after both primary and secondary recrystallization was studied. Despite the percentage of convex boundaries surrounding Goss oriented grains was found slightly higher than that around other grains, it was insufficient to cause abnormal grain growth.

Differences in mechanical properties and high temperature deformation behavior between TiBw/Ti65 and TiBw/TA15 composites with network structure

In this paper, the differences in mechanical properties and high temperature (HT) deformation behavior between TiBw/Ti65 and TiBw/TA15 composites with network structure were studied. The alloy element distribution and microstructure of TiBw/Ti65 and TiBw/TA15 composites were characterized by the electron probe micro analyzer and transmission electron microscopy. The microstructure evolution during HT deformation was analyzed by electron back scatter diffraction. The mechanical properties of two composites were tested at room temperature and 600–750 °C. Arrhenius and artificial neural network models were developed to predict the peak stress and flow stress, respectively. The results show that the multiple alloying elements and silicide in TiBw/Ti65 refined the grains. TiBw/Ti65 composites had higher deformation activation energy and higher strength under the same deformation conditions. Based on the analysis of differences in microstructure, the strengthening mechanisms of TiBw/Ti65 compared to TiBw/TA15 was mainly from fine grain strengthening, dislocation density strengthening, and Orowan strengthening of silicide. The initial recrystallization temperatures for TiBw/TA15 and TiBw/Ti65 were 700 °C and 750 °C with strain rate of 0.001 s−1, respectively. The above results show that TiBw/Ti65 had better HT deformation resistance.

Microstructure, Texture, and Anisotropic Properties of High-Strength Low-Alloy Steel

The effects of cold rolling reduction rates and recrystallization annealing temperature on the microstructure, texture, and anisotropic properties of high-strength low-alloy (HSLA) steel were investigated using scanning electron microscopy and electron backscatter diffraction. The results revealed that the constituents of recrystallized, substructured, and deformed structures were strongly affected by cold rolling reduction rates ranging from 33.3% to 66.7% and recrystallization temperatures ranging from 780 to 840 °C. At an annealing temperature of 820 °C, when the cold rolling reduction rate was 33.3%, HSLA steel exhibited a low percentage of recrystallization, with cubic, γ-linear, rolled, and Z-texture (the texture at Euler angles φ1 = 30° and Φ = 20°–30°) structures. The rolled texture and Z-texture increased the strength anisotropy and disappeared at high cold rolling reduction rates. When the annealing temperature was increased from 780 °C to 820 °C, the proportion of recrystallized grains increased, the rolling texture disappeared, and grain orientation gradually gathered in the cubic texture and γ line texture, resulting in low anisotropy of strength. At an annealing temperature of 840 °C, the deformation of the grain disappeared; however, the anisotropy increased compared to annealing at 820 °C because of the formation of a new texture of {001}&lt;−1–20&gt;.

Evaluation of tensile property and strengthening mechanism of Zirconia reinforced molybdenum alloy

In this experiment, the nano-ZrO2 particles reinforced molybdenum alloy with excellent mechanical properties were prepared through liquid-liquid doping process, and the comparison with TZM alloy prepared by solid-solid doping process was conducted. During the liquid-liquid doping process, the ZrO2 particles ensured the dispersion of the second phase in alloy because they reached molecular-level uniformity, and the hydrothermal synthesis preparation process enabled the ZrO2 particles in alloy to reach nanometer size level. In Mo-ZrO2 alloy, the small and dispersed ZrO2 can effectively block dislocation and passivation cracks; both the room temperature and high temperature performance of Mo-1.5 %ZrO2 alloy was better than that of TZM alloy. Based on the hindered recrystallization process, improved recrystallization temperature, as well as enhanced recrystallization strength thanks to the alloy pinning effect of ZrO2, the maximum tensile stress of Mo-1.5 %ZrO2 alloy at 1000 ℃ was about 14 % higher than pure molybdenum, and the maximum tensile stress of Mo-1.5 %ZrO2 alloy at 1400 ℃ was at least 45 % higher than pure molybdenum. Quantitative analysis shows that the strengthening effect of the second phase was the best during the recrystallization process.

Effect of Sr on Microstructure and Strengthening Mechanism of Al-4.6Mg Alloy.

The as-cast Al-4.6Mg alloy was subjected to deformation and sensitization-desensitization heat treatment, and then the microstructure and the enhancement mechanism of Sr were investigated by optical microscopy, scanning electron microscopy-energy-dispersive spectroscopy, electron backscatter diffraction, and transmission electron microscopy. The precipitation phases of Al-4.6Mg alloy were mainly β-Al3Mg2, Al6Mn, and Al6(Mn Cr), and the nanoscale precipitation phases were Al3Mn and Al11Mn4. The formation of β-Al3Mg2 was hindered by the addition of 0.1 wt.% Sr. In addition, the precipitate phase Al4Sr and the nano-sized precipitate phase τ-Al38Mg58Sr4 were uniformly distributed in the spherical matrix. The addition of Sr promoted the redissolution of Mg atoms in Al-4.6Mg alloy, increasing the solubility of Mg in the α-Al matrix from 4.7 wt.% to 5.1 wt.%. The microstructure analysis showed that Sr addition inhibited the recovery and recrystallization of the alloy because the Sr element elevated the recrystallization temperature. As a result, the grain deformation was intensified, the grain size was decreased from 6.96 μm to 5.39 μm, the low-angle grain boundaries were increased from 78.7 at % to 84.6 at %, and the high-angle grain boundaries were increased from 21.3 at % to 15.4 at %. Furthermore, the mechanical properties of the alloy were significantly improved, and the plasticity degraded after the addition of the Sr element. The yield strength of the alloy was enhanced mainly through fine grain strengthening, dispersion strengthening, solid solution strengthening, and working hardening. The strengthening mechanisms were analyzed in detail.

Solute segregation and nanoparticle dispersion induced super high stability in a bulk nanocrystalline W-based alloy

Improvement of the stability of nanocrystalline (NC) materials is always a challenge. In this paper, the high thermal stability is achieved in a representative NC W alloy by combining nano-segregation of Ti solute to W grain boundary (GBs), and in-situ formation of nano Ti–Zr–O particles, which provide both thermodynamic and kinetic stabilization effects through solute dragging and particle pinning. The recrystallization temperature of this bulk NC W alloy reaches up to 1600 °C, and these nanometric microstructures maintain stable under a long-time and high-temperature ordeal up to 1200 °C for 120 h. And its microhardness and micro-compressive yield strength are ∼17.0 and 5.14 GPa, respectively. In addition, this bulk NC W alloy has high irradiation stability due to the high densities of stabled GBs and phase boundaries. This work demonstrates the possibility of attaining high-stability bulk NC materials in terms of segregation of solutes at GBs and in-situ formation of ultrafine nanoparticles with a coherent interface with the W matrix.

The Impact of Pipe Ø 0,5 Heater Length and Temperature on Ovality and The Difference in Pipe Thickness for Its Bending

Ferrous metal is of material utilized mostly for many objects or kinds of stuff to help humans and their work easier. Low-carbon steel is one of the ferrous metal natures that could be utilized when transforms into more useful objects. There be cold as well as hot working to undertake. Molting by bending pipe includes cold working due to it being bent as its recrystallization temperature is lower. When the process is undertaken, the pipe dimension would be oval which needs to be examined by enumerating a lower-recrystallization temperature and whether or not to shrink the pipe ovality percentage. In addition, as the pipe is bent there would be changes in the pipe dimension because it would drives pulls as well as puts pressure on one of the cross-sectional areas so the pipe percentage of dimension/thickness changes should also be examined. Methods to apply are a series of experiments by firstly treating heating which is up to 650o C and bending pipe as its temperature goes lower between 410o C – 500o C. These two types of independent variables that differ only in their cross-sectional areas of heating also resulted in impacting on both ovality percentage and the pipe thickness of its cross-sectional area.

Effect of Laser Power on the Recrystallization Temperature of an Additively Manufactured IN718

Over the past few decades, there has been much research on additive manufacturing in both the academic and the industrial spheres to overcome the limitations of conventional manufacturing methods, thereby enabling the production of complex designs for improved performance. To achieve this purpose, it is crucial to meticulously set suitable laser parameters within the context of microstructural characteristics, including type and fraction of defects, texture development, residual stress, and grain size, etc. In the present study, we focused on recrystallization behavior, a type of relaxation process for accumulated thermal stress during the L-PBF process, as a function of laser power applied on the L-PBF process. The laser power has significant effects on the amount of recrystallized grain, directly related to the recrystallization temperature. Within the range of laser power used in this study, a downward trend was observed in the recrystallization temperature as the laser power increased from 370 W to 390 W. This trend suggests that higher laser power leads to a faster cooling rate, influenced by the volume of melt pool as well as the amount of heat dissipation from the melt pool, resulting in higher thermal stress during the process.

The orientation dependence of stored energy and the evolution of texture of through-thickness tantalum targets during heating

In semiconductor integrated circuits, the orientation dependence of the stored energy and texture distribution uniformity of sputtering tantalum targets are critical to the properties of the deposited films which block the diffusion of Cu atoms into the storage cell Si. In this paper, the effect of heating rate on the recrystallization behavior was investigated with the aid of a differential scanning calorimeter (DSC). In addition, the texture and stored energy of deformed tantalum targets with different heat treatments along the thickness direction were characterized using electron backscatter diffraction (EBSD). The results show that the initial temperature of recrystallization rises but the temperature range reduces with the increase of the heating rates. The stored energy of deformed tantalum targets presents various orientation dependencies in different thickness layers. During the heating process, the stored energy difference among the grains with different orientations decreases, but the maximum difference of stored energy in different thicknesses increases inversely. The content of {101} oriented grains increases as the temperature increases, while the content changes of {111} and {001} present a waveform with an opposite trend.

Deformation localization behavior research of AZ31 magnesium alloy under impact load

The dynamic mechanical properties of AZ31 magnesium alloys were analyzed under different strain rates by using a separated Hopkinson pressure bar system. The microstructure of the specimens was observed by optical microscopy. The results show that the dynamic yield strength of AZ31 magnesium alloy is insensitive to the strain rate. The compressive strength is increasing and shear deformation localization behavior is more obvious with the increase in the strain rate. Meanwhile, the temperature within the shear band is about 241 k and meets the twinning dynamic recrystallization temperature. Temperature rise promotes the grain refining effect.

EFFECT OF ULTRAFAST HEATING ON AISI 304 AUSTENITIC STAINLESS STEEL

This study explores the effects of ultrafast heating on AISI 304 austenitic stainless steel. The research shows that ultrafast heating can lead to fine-grained mixed microstructures in steel, making it a potential alternative for modifying microstructure in stainless steel. The study demonstrates that a minimum temperature of 980 °C is required to achieve a fully recrystallized microstructure. The results also suggest that a lower temperature can result in a finer recrystallized grain size compared to higher temperature results. The study provides valuable insights into the impact of ultrafast heating on the microstructural constituents, recrystallization temperatures, and mechanical properties of investigated steel.

The Microstructural and Hardness Changes of Tungsten Fiber after Au2+ Irradiation

Tungsten fiber-reinforced tungsten composite (Wf/W) material is considered a plasma-facing material (PFM) with good application prospects. Commercial tungsten wire (fiber) prepared through forging and drawing processes has excellent mechanical properties, as well as a very high recrystallization temperature due to the unique texture of it grain structure. Commercial tungsten fiber is the most proper reinforcement for Wf/W. The change in the properties of tungsten fiber because of neutron irradiation makes it inevitable for Wf/W to be used as PFMs. However, there is very little research on the change in the properties of tungsten fiber caused by neutron irradiation. In this work, we used heavy ion irradiation to simulate the displacement damage generated by neutron irradiation to explore the alteration of the properties of a commercial tungsten fiber caused by neutron irradiation. The investigated subject was tungsten fiber with a diameter of 300 μm. The irradiation source was 7.5 MeV Au2+, which generated a maximum displacement damage of 60 dpa at a depth of 400 nm, and the irradiation influenced depth was 1000 nm. Because of the irradiation, significant lattice distortion occurred within the tungsten fiber, resulting in the transition from (110) texture to (100) texture at the fiber’s cross-section. The results of the Schmidt factor and Taylor factor analysis indicate a decrease in the plasticity of the tungsten fiber after irradiation, but it did not completely lose its plasticity. The results of the nanoindentation test confirmed the radiation hardening. After irradiation, the hardness of the tungsten fiber increased by approximately 0.33 GPa, but this increase was relatively small compared to other tungsten-based materials. This indicates that commercial tungsten fiber is a low-cost and highly reliable reinforcement material for Wf/W composite materials.

Insight into microstructure evolution and mechanical properties of 5 wt% SiC/Al composites by high frequency pulse current treatment

In order to improve the status of stress concentration and anisotropy of the as-rolled SiC/Al composites, high frequency pulse current was employed to modify the microstructure and mechanical property. Results show that the skin effect makes the current concentrate on the surface zone. The high density current makes the static recrystallization of 35.8% occurred under the condition that the surface temperature is much lower than that of recrystallization temperature of Al alloy, and the grain size is refined from 2.52 μm to 2.06 μm. The obvious recrystallization behavior in the surface area indicates that the non-thermal effect plays a dominant role in the pulse current treatment process. As a contrast, subgrains growth and partial recrystallization occurred in the internal region and transition region under the non-thermal effect, resulting in a slight increase in average grain size to 2.78 μm and 2.75 μm. Nano-indentation results show that the micro-hardness and the indention work recovery rate in the surface area reach 2.09 GPa and 39.8%, respectively, which are 48.2% and 29.2% higher than that of the as-rolled composites, which proves that the mechanical properties have been improved comprehensively compared with as-rolled composites.