Short-time Annealing Research Articles

Impact of Irreversible Adsorption on Molecular Ordering and Charge Transport in Poly(3-hexylthiophene) Thin Films on Solid Substrates.

We investigate the irreversible adsorption of poly(3-hexylthiophene) (P3HT) polymer thin films on silicon dioxide/silicon (SiO2/Si) substrates during thermal annealing at a temperature below the melting temperature (Tm) but far above the glass transition temperature (Tg), i.e., Tg ≪ T = 170 °C < Tm, and its effect on their crystalline ordering and charge transport properties. It was found that short-time annealing enhances the molecular ordering of P3HT films, while prolonged thermal annealing gradually disrupts the crystalline structures and reduces the overall crystallinity of the film. Concurrently, thermal annealing at this temperature facilitates the slow irreversible adsorption of P3HT chains at the polymer-solid interface, resulting in the formation of a 1.7 Rg-thick (∼18 nm thick) adsorbed layer on SiO2/Si substrates that is fully amorphous and contains a large fraction of loosely adsorbed chains. We postulate that such irreversible adsorption is responsible for the reduced crystalline packing of P3HT at the polymer-solid interface at Tg ≪ T < Tm, which further disrupts the molecular ordering of the entire 46 nm thick P3HT film by a long-range perturbation effect. Electrical measurements using an organic field-effect transistor (OFET) device reveal that the enhanced charge carrier mobility of P3HT films correlates with an optimized annealing time at Tg ≪ T < Tm, which achieves a balance between maximizing molecular ordering and minimizing the impact of irreversible chain adsorption. These findings provide new insights into the underlying mechanism of thermal annealing in tailoring the structure and property of conjugated polymer thin films prepared on solid substrates.

Enhanced energy harvesting of fibrous composite membranes via plasma-piezopolymer interaction

Electroactive sites and crystallinity play a key role to improve the energy conversion performance of piezoelectric polymeric composites. However, these characteristics are attained through time-consuming thermal annealing (TA), which limits the practicality of flexible piezoelectric harvesters (f-PEHs). Here, a short-time plasma annealing (PA) technique was introduced to piezoelectric composite fibers (PCFs) for rapid crystallization and enhanced electroactive β-phase of polymer. The percentage of change in crystallinity of 10-minute PA treated PCF is 20 % compared to TA-treated PCF (annealing time = 2 h), which results in a higher voltage of 2.4 times and current of 3.8 times than the TA-based f-PEH. Finite element analysis confirmed the optimal PA treatment duration and superior performance of PA-treated PCFs. Further PA treated f-PEH was tested for vibration sensor by attaching it to a circulator pipe, confirming its high potential for accurately detecting variations in flow velocity (8–28 L/min). These results demonstrate that PA is an efficient technique for producing high-performance f-PEHs with an increased crystallinity (Xc =22.81 %) in a short time (10 minutes), offering a practical solution for consumer electronic devices and wireless sensors.

Effect of microstructural inheritance window on the mechanical properties of an intercritically annealed Q&P steel

Different initial microstructures significantly influence the final microstructures and mechanical properties of the intercritically annealed quenching and partitioning steels. Previous studies have primarily focused on the mechanism for the inheritance of different initial microstructures into the final microstructures, which affects the phase fraction and mechanical properties. However, these studies have overlooked the existence of an inheritance window in the intercritical annealing process. In this study, we investigated the inheritance window and explored the impact of varying initial microstructures on the reverse transformation of austenite, final phase fraction, and mechanical properties. Our findings reveal that the varying initial microstructure exhibits minimal influence on the final microstructure and mechanical properties for short or long annealing times. However, for the intercritical annealing treatment for 60 s, the initial microstructure of martensite with more nucleation sites accelerated the austenite reverse transformation fraction, enhanced the reverse-transformed austenite content, increased the primary martensite content, and improved the yield strength. Conversely, the coil-cooled sample, with initial microstructures consisting of ferrite and pearlite without dissoluble Mn-rich cementites, reduced the austenite reverse transformation rate, decreased the reverse-transformed austenite content, enhanced the ferrite and RA content, and improved ductility.

Early-stage diffusion and oxidation behavior of Cr-Nb coated Zr alloy accident tolerant fuel cladding materials at 1200°C–1500°C

Although the Cr-coated Zr alloys are considered as the most promising accident tolerant fuel cladding materials in recent years, the Cr-Zr interdiffusion problem is a major obstacle for the widely used of the Cr coating. In this study, Cr-Nb coated Zr alloy samples were prepared by magnetron sputtering. The Nb layer was designed as a barrier layer to retard the Cr-Zr interdiffusion. By using a fast-in and fast-out equipment, short time annealing was conducted in argon environment to study the coating evolution in high temperature environment. Results show that the Nb coating can retard the inward diffusion of Cr because of the low diffusion coefficient of Cr in the Nb layer. However, the complete miscibility between Nb and Zr lead to the fast consumption of the Nb coating. After 10 min annealing at 1200 °C, the 2.5 μm Nb coating disappeared, and a Cr-Zr-Nb mixed phase formed between the residual Cr coating and Zr substrate. The early-stage microstructure evolution of the sample was analyzed, and the barrier effect of the Nb coating was summarized.

Enhancing the corrosion resistance of high Mo S31254 super austenitic stainless steel using grain boundary engineering

Super austenitic stainless steel (SASSs) with a high Mo content exhibit excellent resistance to intergranular corrosion (IGC), Its mechanical properties mainly depend on solid solution strengthening. Meanwhile, grain boundary engineering (GBE) can simultaneously improve the corrosion resistance and mechanical properties of Mo-rich austenitic stainless steel using the resistance to IGC of Mo. However, recrystallization annealing is extremely difficult due to the sensitive precipitation of Cr-rich and Mo-rich precipitations in SASSs. Therefore, this study explores the effect of large deformation, high temperature, and short-time annealing on the corrosion resistance of SASSs. The results show that a recrystallized organization with an average grain size of 13.3 μm was prepared by 50% cold rolling deformation and 2 min high-temperature short-time annealing at 1150 °C. The highest percentage of Σ3 GBs is about 34%, the percentage of other low-energy GBs is relatively low (only about 6%), and the rest are random high-angle grain boundaries (RHAGBs), which account for about 60%. It can be seen the corrosion resistance of random GBs after GBE treatment is superior to that of solution treatment. Meanwhile, medium-temperature aging improved the resistance to IGC of SASSs, especially after aging at 450 ℃, a small amount of Mo is enriched along the GBs, which promotes the formation of Cr2O3 and Mo-rich oxides in the passivation film and improves the corrosion resistance. The above results provide guidance for improving the corrosion resistance of Mo-rich austenitic stainless steels.

Coupling effects of multiple strengthening mechanisms in spheroidal microstructure eutectic high-entropy alloys

The yield strength of metallic materials is commonly estimated using linear superposition methods, but this method has limited adaptability to new materials. The mapping relationship between input and output in machine learning methods is difficult to quantify. This study employs a rapid screening method to identify the key strengthening mechanisms that influence the yield strength of typical homogeneous and heterogeneous metallic materials. A non-linear physical neural information network model is developed to describe the yield strength of heterogeneous structures, capturing the main parameters contributing to yield strength from selected physical quantity data. By considering the non-linear strengthening mechanisms arising from interactions among multiple strengthening mechanisms in heterogeneous metal structures, the microstructure and mechanical properties of eutectic high-entropy alloys are optimized through warm rolling and short-time annealing. By inducing microstructural spheroidization and introducing nanoscale precipitates, significant coupling effects of multiple strengthening mechanisms are achieved for eutectic high-entropy alloys. As a result, the yield strength increases by approximately 2.5 times, while plasticity remains nearly unchanged. Transmission electron microscopy, scanning electron microscopy, and electron backscatter diffraction observations provide evidence for the sources of these coupling effects. This study offers guidance for accelerating material design and exploring the physical relationship between microstructure and mechanical properties.

Effect of isothermal annealing on formation of self-assembled nanostructures in manganese spinel ZnMnGaO4

The effects of isothermal annealing on the self-assembled nanostructures of spinel manganese oxide ZnMnGaO4 were investigated using transmission electron microscopy and x-ray diffraction. The checkerboard nanostructures and zigzag nanostructures (named “Sierra” nanostructures) coexisted owing to the chemical phase separation of Mn3+ and Ga3+ ions by isothermal annealing at 575 °C. It was observed that the checkerboard nanostructures were dominant in short-time annealing and that the volume fraction of the Sierra nanostructures became more prominent as the annealing period increase. The interdiffusion of Mn3+ and Ga3+ is indicated to play an important role in gaining the total energy of the system by the reduction in the local strain caused by the formation of nanostructures. These results provide further insights into the fabrication of distinct types of nanostructures in complex transition-metal compounds.

TEM Image Analysis and Simulation Physics for Two-Step Recrystallization of Discretely Amorphized C3H5-Molecular-Ion-Implanted Silicon Substrate Surface

In this study, we investigate the initial rapid recrystallization of a discretely amorphized C3H5-molecular-ion-implanted silicon (Si) substrate surface in the subsequent thermal annealing treatment through the analysis of plan-view transmission electron microscopy (TEM) images and technology computer-aided design (TCAD) process simulation. In the approach of the analysis of the plan-view TEM image of the Si substrate surface, we found that initial rapid recrystallization occurs in the intermediate regions between the residual crystalline and discrete amorphous regions formed in the C3H5-molecular-ion-implanted Si substrate surface. In addition, the TCAD process simulation results indicate that the intermediate regions correspond to the amorphous pockets formed around the discrete amorphous regions in the C3H5-molecular-ion-implanted Si substrate surface and are recrystallized preferentially during the short thermal annealing time. These plan-view TEM image analysis and TCAD process simulation results reveal a two-step recrystallization of the discretely amorphized C3H5-molecular-ion-implaned Si substrate surface. After the initial rapid recrystallization of amorphous pockets in the 1st step, the recrystallization of discrete amorphous regions starts in the 2nd step. The incubation period between the 1st and 2nd steps is the time required to recrystallize the amorphous pockets around the discrete amorphous regions completely and redefine the amorphous/crystalline interface.

Effect of low and high temperature ECAP modes on the microstructure, mechanical properties and functional fatigue behavior of Ti-Zr-Nb alloy for biomedical applications

A Ti-18Zr-15Nb (at%) shape memory alloy was subjected to a high-temperature thermomechanical treatment (HTMT) combining an equal channel angular pressing (ECAP) at 500 °C for n = 4–8 passes and a short-time post-deformation annealing (PDA) at 600 °C. The phase composition, microstructure, texture, mechanical and functional properties were studied. The functional fatigue behavior observed in this study was compared to that resulted from the reference low-temperature thermomechanical treatment (LTMT) by ECAP at 200 °C for 3 passes + PDA (600 °C for 5 min). The ECAP at 500 °C (n = 4) led to the formation of a highly deformed, dynamically polygonised substructure of β-phase with a crystallographic texture close to the [101] direction. In this state, the alloy exhibited an excellent combination of the static functional and mechanical properties: a relatively high strength (UTS = 670 MPa), a sufficient ductility (δ = 13.3 %), a low Young’s modulus (E < 40 GPa), and a high superelastic recovery strain (εrsemax= 3.1 %). An increase in the number of passes during ECAP to n = 8 led to a greater substructural hardening of the material, grain/subgrain refinement, and the release of α-phase. This significantly increased the alloy strength (UTS = 897 MPa), but reduced its ductility (δ = 5.9 %) and suppressed martensitic transformation. The alloy after both the HTMT (ECAP at 500 °C, n = 4) and TMT (ECAP at 200 °C, n = 3) processes exhibited an equally excellent functional fatigue resistance accompanied by a superior superelastic behavior with small accumulated strains. However, the HTMT process appears to be more technologically advanced, as it eliminates the need for PDA and reduces the risks of specimen cracking during processing.

Multiple cycles of combined cold rolling and short-time annealing on the microstructure and properties evolution of NiAl bronze

In this study, three cycles of combined cold rolling and annealing (CRA) were applied to study the mechanical behavior of NiAl bronze (NAB) alloy. The underlying mechanisms for microstructure and mechanical properties were elucidated. Microstructure characterization and quantitative analysis demonstrated significant morphology changes by CRA. The results showed that large α-Cu phase is compressed, lamellar κIII phase is broken and sphericalized, and κII phase accumulates and forms a hard phase band skeleton. Finally, the microstructure with spheroidized κIII phase embedded in the skeleton of the κII phase is obtained. The optimal ultimate tensile strength of 903 MPa and yield strength of 596 MPa are obtained after one cycle of CRA, which exhibits an improvement of about 40 % and 130 % compared to the as-cast samples, respectively. The best ductility of 18.0 % is obtained after three cycles of CRA, with an improvement of about 75 % over the as-cast samples. The high strength is mainly attributed to the grain refinement and high density of dislocations. Additionally, the higher density of low-angle grain boundaries can promote the formation and growth of twins. The saturation fraction of twin boundaries in experimental alloys of about 66 % is achieved after two cycles of CRA.

Optimization of Activation Annealing Condition for Boron‐Implanted Diamond

Impurity activation of dopants implanted in diamond is one of the crucial issues for device application of diamond. Boron impurity atoms are introduced in diamond, which expectedly act as acceptors, by ion implantation technique, and are investigated the optimum annealing time for the effective dopant activation. The impurity doping is performed by boron ion implantation at multiple incident energies to obtain a uniform dopant concentration from the surface to 350 nm depth followed by activation annealing at 1300 °C for 5–240 min. The electrical properties of specific resistance, carrier concentration, and conduction type are analyzed as a function of temperature from room temperature to 873 K. The estimated ionization energy is strongly dependent on the annealing time and asymptotically approaches to 0.3 eV, which is theoretically expected ionization energy of acceptor boron, with increasing annealing time. A shorter annealing time ( does not sufficiently recover radiation damages caused by ion implantation forming deep levels, which act as irregular conduction. It is consequently found that an optimum window of annealing time for effective dopant activation and suggested carrier transport mechanisms depending on the annealing time.

Achieving High Strength and Tensile Ductility in Pure Nickel by Cryorolling with Subsequent Low-Temperature Short-Time Annealing

Ultrafine-grained pure metals and their alloys have high strength and low ductility. In this study, cryorolling under different strains followed by low-temperature short-time annealing was used to fabricate pure nickel sheets combining high strength with good ductility. The results show that, for different cryorolling strains, the uniform elongation was greatly increased without sacrificing the strength after annealing. A yield strength of 607 MPa and a uniform elongation of 11.7% were obtained after annealing at a small cryorolling strain (ε = 0.22), while annealing at a large cryorolling strain (ε = 1.6) resulted in a yield strength of 990 MPa and a uniform elongation of 6.4%. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD) were used to characterize the microstructure of the specimens and showed that the high strength could be attributed to strain hardening during cryorolling, with an additional contribution from grain refinement and the formation of dislocation walls. The high ductility could be attributed to annealing twins and micro-shear bands during stretching, which improved the strain hardening capacity. The results show that the synergistic effect of strength and ductility can be regulated through low-temperature short-time annealing with different cryorolling strains, which provides a new reference for the design of future thermo-mechanical processes.

Annealing parameters effect on microstructure evolution, tensile properties and deformation behaviors of direct-cold-rolled UNS S32101 duplex stainless steel with heterogeneous layered structure

Microstructure evolution, strain-induced martensite transformation (SIMT) kinetics, tensile properties, deformation behaviors of UNS S32101 duplex stainless steel (DSS) with heterogeneous layered structure (HLS) were investigated. HLS composed of multiscale grains (spanning coarse, fine, and ultrafine grains) was prepared by direct cold rolling in combination with short-time annealing, being dominated by coarse-grained ferrite (CGed α) and fine-grained austenite (FGed γ). A quantitative SIMT kinetics model was established to predict the α′-martensite fraction at various strain/annealing parameters, indicating that increased average grain size (AGS) for γ not only contributed to the SIM formation but also promoted the monotonic increase of SIMT rate until annealing for 10 min. Relatively high stacking fault energy (SFE, 35.89∼39.34 mJ/m2) favored mechanical twinning as the dominant deformation mode of γ accompanied by SIMT and dislocation glide. And α deformation was mainly coordinated by wavy slip. Both SFE and Olson-Cohen parameters were strongly correlated with the γ AGS, which could reasonably interpret the dependence of SIMT on the AGS. The A and B values increased progressively with grain coarsening along with the rapid decline in SFE, facilitating the martensite formation. Further increasing the AGS beyond the peak region severely suppressed SIMT probably due to the low probability of martensite embryo generation at deformation twins (DTs) intersections, coinciding with the sharp decrease A value.

Study on thermal stability and biocompatibility of bimodal microstructure in Cr–Mn–N austenitic stainless steel

Heterostructured austenitic stainless steels (ASS) are becoming a significant research area because of their outstanding mechanical properties and considerable potential for various applications. However, the thermal stability of heterogeneous microstructures, particularly the bimodal microstructure, has received limited attention and lacks systematic investigation. Additionally, there is a scarcity of reports regarding the biocompatibility of bimodal microstructures. Herein, the thermal stability and biocompatibility of the bimodal microstructure prepared by cold rolling and annealing in Cr–Mn–N series ASS (without and with Nb microalloying) are studied. The findings demonstrate that the bimodal microstructures of ASS are formed after annealing at 700 °C, 800 °C, and short-time annealing at 900 °C. Moreover, the addition of Nb significantly enhances the thermal stability of the bimodal microstructure and maintains the bimodal feature up to 1000 °C. The thermal stability of bimodal microstructures depends on the competition in coarse and fine grains growth. The good thermal stability of Nb(C, N) at high temperatures leads to consistently higher pinning force within the fine-grained zone. As a result, the growth of fine grains lags behind that of coarse grains, which leads to the persistence of bimodal microstructure at higher temperatures. The bimodal microstructure of ASS demonstrates superior biocompatibility, attributed to its ability to promote higher cell viability, exhibit stronger fibronectin intensity, and facilitate a wider fibronectin expression network in osteoblasts. These characteristics make the bimodal ASS more favorable for osteoblast attachment and proliferation compared to its coarse-grained counterpart. This study significantly enhances our understanding of the thermal stability and cellular functionality of bimodal ASS, highlighting its potential for various biomedical applications.

Multiple effects of forced cooling on joint quality in coolant-assisted friction stir welding

To understand the multiple effects of forced cooling on the joint quality in coolant-assisted friction stir welding and the underlying mechanism, commercial pure aluminum AA1050 was welded by liquid–CO2–assisted friction stir welding (FSW) within a large process parameter range. The cooling effects on the weld formation, microstructure, and mechanical properties were investigated by comparison with conventional FSW. The microstructure evolution during the liquid–CO2–assisted FSW process was revealed by EBSD characterization together with thermal cycle measurement and short-time annealing. The results show that the process parameter window was narrowed by the liquid CO2 cooling. Forced cooling led to weld surface grooves and interior cavities under “too cold” welding conditions. The grains in the weld zone were refined and the areas of the weld cross-section were reduced by the forced cooling, resulting in the tensile strength of the joint being improved but the elongation being reduced. The thermal cycle shows that the liquid CO2 cooling compressed the welding temperature field by decreasing the heating rate and increasing the cooling rate, giving rise to the decrease in deformation temperature at the stirring stage. The low deformation temperature promotes dynamic recrystallization by changing the way of recrystallization and thus refines the grains. Further, the liquid CO2 cooling suppresses the grain growth which should have happened in natural cooling. Combining the above two aspects, the grain in the weld zone was refined and the tensile properties of the joints were changed. Nevertheless, the contribution of decreasing the deformation temperature to the grain refinement is more significant than that of increasing the cooling rate.

Influence of Heat Treatment Parameters of Austempered Ductile Iron on the Microstructure, Corrosion and Tribological Properties.

The influence of heat treatment parameters such as the annealing time and austempering temperature on the microstructure, tribological properties and corrosion resistance of ductile iron have been investigated. It has been revealed that the scratch depth of cast iron samples increases with the extension of the isothermal annealing time (from 30 to 120 min) and the austempering temperature (from 280 °C to 430 °C), while the hardness value decreases. A low value of the scratch depth and a high hardness at low values of the austempering temperature and short isothermal annealing time is related to the presence of martensite. Moreover, the presence of a martensite phase has a beneficial influence on the corrosion resistance of austempered ductile iron.

Evolution of microstructure and mechanical properties during short-time annealing of a hard-plate rolled 2 vol% TiCp/near-β titanium matrix composite

In this study, to suppress the edge cracks and efficiently improve the mechanical properties, hard-plate rolling and subsequent short-time annealing were conducted on the 2 vol% TiCp/near-β titanium matrix composites, and the effects on the microstructure and mechanical properties were investigated systematically. The results show that the TiCp are arranged along the rolling direction, some primary α phases are elongated into fiber-like, and β grain boundaries are not visible. The static recrystallization and recrystallization textures are developed after a short time of annealing in the β phase region of the hard-plate rolled plates. After annealing, the α phases disappear, the new β recrystallized grains replace the deformed ones, and the texture strength of γ fiber ({111}<112> component) is enhanced. The ductility of hard-plate rolled plates increases while the strength decreases after annealing, but the ductility starts to decrease with the completion of recrystallization and grain growth. After annealing at 860 °C for 1 min, the average size of β grain is about 9.8 μm and the properties of the samples are better optimized than those after hard-plate rolling. The ultimate tensile strength decreases from 1564 MPa to 1337 MPa, and the elongation increases from 2.8% to 7.8%. The application of hard-plate rolling and short-time annealing processes can refine grain effectively and improve the properties of plates.

Achieving excellent strength-ductility synergy via cold rolling-annealing in Al-containing refractory high-entropy alloys

Most refractory high-entropy alloys (RHEAs) with Al possess excellent strength but low elongation. Low ductility is generally induced by the formation of brittle phases after long-term heat treatment. Here, we demonstrate a new strategy to optimize strength-ductility in RHEAs through cold rolling-annealing treatments. The Zr35Ti30Nb20Al10Ta5 RHEA was cold rolled followed by annealing. A high tensile yield strength of ∼997 MPa with an elongation of ∼20% was obtained. Several factors together optimize the mechanical properties. First, the high-density dislocation entanglements introduced by cold rolling and short-time annealing are beneficial to uniform strain hardening and ductility. Second, short-term annealing can prevent the generation of the brittle LAVES phase in Al-containing RHEAs. Third, the B2 nanoprecipitates are dispersed in the BCC matrix phase, strengthening the alloys. Fourth, the fine grain size induced by cold rolling and short annealing times contributes to the strength.

Microstructure evolution and mechanical properties of Mg-3Al-3Sn-1Zn alloy during multi-pass high-speed rolling

The microstructure evolution and mechanical properties of as-homogenized Mg-3Al-3Sn-1Zn (ATZ331) alloy with an initial grain size of ∼126.7 µm are studied during multi-pass high-speed rolling (HSR) process. The main deformation mechanism governing the microstructure is comprised of twinning and dislocation migration, Firstly, high dislocation density and twinning generated during HSR. Then, the dislocations are rearranged and incorporated as subgrain boundaries (sub-GBs), leading to a reduction of grain size with an increase in rolling pass. Results show that a fine and uniform microstructure (1.1 µm) of HSRed ATZ331 is achieved after the sixth pass, with a yield strength (YS), ultimate tensile strength (UTS), and elongation to failure (FE) of 319 MPa, 360 MPa, and 5.9 %, respectively. After being subject to HSR, low-temperature short-time annealing is carried out in order to improve ductility, which has proven to bring about sufficient static recrystallization (SRX). The SRX mechanism of ATZ331 alloy after HSR processing is found to consist of the classical recovery followed by recrystallization. Subgrains are formed by the realignment and absorption of the accumulated dislocations, which is followed by the migration of low angle grain boundaries (LAGBs) and their transformation into high angle grain boundaries (HAGBs). Finally, the sample with fine average grain size (1.7 µm) is achieved. Furthermore, the YS, the UTS, and the FE of ATZ331 are 253 MPa, 313 MPa, and 9.8 %, respectively.

Microstructure and texture evolution of pure nickel during cryorolling and subsequent annealing

The microstructure and texture evolution of pure nickel sheets during cryorolling and subsequent short-time low-temperature annealing were analyzed by electron backscatter diffraction technique. Results show that the content of typical texture of brass, copper, S, cube, and Goss texture is no significant change during cryorolling with a reduction of 40%. When the reduction reaches 60%, it begins to significantly increase, and when the reduction reaches 80%, it exhibits a copper type texture. However, when the reduction is 20%, the fiber texture of <110>//normal direction (ND) orientation begins to significantly increase, which was mainly caused by dislocation slip during cryorolling. During low temperature and short time annealing, the content of typical textures decreases except S texture, and the grain changes mainly occur in grains other than <110>//ND orientation which is due to the rich substructure and high dislocation density formed in the cryorolling process leading to rapid response to annealing.