Preferential Grain Growth Research Articles

Crystallographic Orientation of Grains Formed in the Laser Melt-Pool of (CoCuFeZr)17Sm2 Anisotropic Permanent Magnets

Textured microstructures and anisotropic properties are key factors for the optimization of magnetic materials. Only for high texture grades can the remanence Jr and the maximum energy product (BH)max be maximized. In additive manufacturing such as laser powder bed fusion (PBF-LB), methods to achieve texture have to be developed. In this work, anisotropic (CoCuFeZr)17Sm2 sintered magnets have been used as a substrate in experiments featuring single laser tracks to study the relationships between crystallographic orientation of the substrate grains and crystallographic orientation of grain growth in the melt-pool. The <0001> crystal direction (c-axis) of the substrate has been systematically varied with respect to the orientation of the laser scan track on the specimen surface. Crystallographic orientations of the melt-pool and the substrate have been analyzed using electron backscatter diffraction (EBSD). It is found that if the c-axis is oriented perpendicular to the temperature gradient in the melt-pool, grains grow with orientation similar to that of the substrate grain. If the c-axis and the temperature gradient are oriented in the same direction, the grains grow with high misorientation to the substrate. The highest anisotropy in the melt-pool is achieved when the substrate’s c-axis is oriented along the laser scan track. Under these conditions, 98.7% of the melt-pool area shows a misorientation <45° compared to the substrate orientation. The texture grade of the melt-pool area is comparable to that of the substrate magnet, at 91.8% and 92.2%, respectively.

Unexpected texture transition induced by grain growth during static annealing of a dilute Mg-1Al alloy

Conventional rolled Mg-Al alloy sheets typically exhibit strong basal textures that remain and may even strengthen after recrystallization annealing due to the preferential growth of basal-oriented grains, resulting in poor formability at room temperature. Therefore, the knowledge of recrystallization and grain growth is critical for modifying textures of Mg-Al alloy sheets. The static recrystallization and texture evolution in a cold-rolled dilute Mg-1Al (wt.%) alloy during various annealed temperatures ranging from 300 °C to 450 °C, have been investigated using the quasi in-situ electron backscatter diffraction (EBSD) method. The as-rolled Mg-1Al alloy shows a dominant basal texture, which weakens and broadens in the rolling direction (RD) during the subsequent annealing, accompanied by the formation of 〈101¯0〉 texture component. Particularly, the 〈101¯0〉 texture component is more pronounced after annealing at high temperatures. The quasi in-situ EBSD results show that recrystallized grains are mainly induced by shear bands, which exhibit a wide spectrum of orientations with c-axis tilt angles ranging 20°-45° from the normal direction (ND). Orientations of shear band-induced recrystallized grains are retained during the entire recrystallization process, resulting in a reduction in the texture intensity. Moreover, recrystallized grains belonging to the 〈101¯0〉 texture component grow preferentially compared to those with other orientations, which is attributed to low energy grain boundaries, especially grain boundaries with ∼30° misorientation angles. Furthermore, the high temperature annealing facilitates the rapid growth of grain boundaries having a 30° misorientation angle, leading to the occurrence of distinct 〈101¯0〉 texture after annealing at 450 °C for 1 h. The results provide insights for texture modification of rare earth-free low-alloyed Mg alloys by controlling annealing parameters.

4‐Phenylthiosemicarbazide Molecular Additive Engineering for Wide‐Bandgap Sn Halide Perovskite Solar Cells with a Record Efficiency Over 12.2%

AbstractThe utilization of wide bandgap (WBG) tin halide perovskites (Sn‐HPs) offers an environmentally friendly alternative for multi‐junction Sn‐HP photovoltaics. Nonetheless, rapid crystallization leads to suboptimal film morphology and substantial creation of defect states, which undermine device efficiency. This study introduces 4‐Phenylthiosemicarbazide (4PTSC) as an additive to achieve a densely packed Sn‐HP film with fewer imperfections. The strong chemical coordination between SnI2 and the functional groups S═C─N (Sn···S═C─N), NH2, and phenyl conjugation enhances solution stability and supports the delay of perovskite crystallization through adduct formation. This process yields pinhole‐free films with preferred grain growth. 4PTSC acts as a strong coordination complex and a reducing agent to passivate uncoordinated Sn2+ and halide ions and reduce the formation of SnI4, thereby reducing defect formation. The π‐conjugated phenyl ring in the 4PTSC facilitates the preferred crystal growth orientation of perovskite grains. Furthermore, the hydrophobic nature of 4PTSC mitigates Sn2+ oxidation by repelling moisture, enhancing stability. The open circuit voltage significantly increased from 0.78 to 0.94 V, resulting in achieving the champion efficiency of 12.22% (certified 11.70%), surpassing all previously reported efficiencies for WBG Sn halide perovskite solar cells. Additionally, the unencapsulated 4PTSC‐1.0 device maintained outstanding stability over 1200 h under ambient atmospheric conditions.

Micro-structure tuning and evolution of hydroxide precursor with radially oriented grains during industrial-scale continuous precipitation process

Constructing hydroxide precursors with radially oriented primary grains is the key factor for fabricating Ni-rich cathodes with sufficient cycle life. Herein, hydroxide precursors with composition of Ni0.92Co0.04Mn0.04(OH)2 were synthesized to study the effects of pH and ammonia concentration on the phase, morphology, and orientation of grains, as well as the evolution of primary grains and secondary particles during industrial-scale continuous precipitation process. Results show that the preferential growth of primary grains varies significantly with change of pH, ammonia concentration and the growth of secondary particles. Meanwhile, the variation of grain size along direction parallel to [001] is more obvious than that perpendicular to [001] after decreasing pH or increasing ammonia concentration. Moreover, the size distribution of secondary particle varies with the increase of feeding time or the change of reaction condition in a regular manner. Although a steady state could be reached for continuous precipitation, the different residence times endow the size of secondary particles with normal distribution. The results disclosed in this work may provide a guiding significance for designing precipitation procedure for hydroxide precursor of high-end Ni-rich cathodes.

Optimizing physico-chemical properties of hierarchical ZnO/TiO2 nano-film by the novel heating method for photocatalytic degradation of antibiotics and dye

The design of semiconductor catalysts with excellent photocatalytic properties, stability, recyclability, and good separation for the treatment of polluted water is still challenging. In this paper, the ZnO/TiO2 nano-thin films were fabricated using the magnetron sputtering technique and then heating the underlying ZnO layer and the upper TiO2 layer for their respective optimal heating time, i. e. heating ZnO for 3 h and heating TiO2 for 2 h. The as-prepared films were characterized. The results show that the preferred growth of TiO2 grains along the [001] axis, relatively large specific surface area, and increased amounts of surface oxygen vacancies (OVs) were induced to the heterojunction catalysts through this optimized heating strategy, which boosts the photocatalytic activity of ZnO/TiO2 nano-film. The degradation experiment inndicates that the ciprofloxacin (CIP) removal efficiency can reach 97.3% in 2 h duration, which was higher than that of the samples annealed for the same periods. Meanwhile, the prepared ZnO/TiO2 photocatalytic film exhibited favorable stability of 95.5% degradation efficiency after the fourth run and general applicability for the photodegradation of various contantains, whih removed 99.5% of ofloxacin (OFX) and 77.6% of tetracycline (TC) in 2 h and 94.1% of Rhodamine B (RhB) in 1 h. This work is expected to yields a novel insight into the production of heterojunction photocatalysts with excellen ability for photocatalytic degradation of pollutants in the practical industry.

Performance of Ni–SiC composites deposited using magnetic-field-assisted electrodeposition under different magnetic-field directions

To improve the surface and structure performances of metal parts, magnetic-field-assisted electrodeposition was applied to deposit the Ni-SiC composites on Q235 steel substrates. The surface morphology, roughness, microstructure, abrasion resistance, and corrosion resistance of the composites were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), hardness and friction wear tests, and electrochemical analysis, respectively. The Ni-SiC composite (MC-1) fabricated at 0.5 T with perpendicular magnetic direction exhibited a smooth, dense, and fine surface morphology, the highest SiC content, and a Ni grain size of only 72.3 nm. Furthermore, AFM images showed that the roughness of the MC-1 composite (Ra of 84 nm) was lower than those of Ni-SiC composites deposited at 0 T and 0.5 T. XRD analysis indicated that the application of a perpendicular magnetic field changed the preferred growth of Ni grains from the (200) to (111) crystal plane. MC-1 had the highest microhardness and lowest friction coefficient of all composites, indicating its superior abrasion resistance. Furthermore, the MC-1 composite had the lowest corrosion current (0.466 μA/cm2) and highest corrosion potential (−254 mV), indicating its superior corrosion resistance compared to the other composites.

Phase Structure, Microstructure, Corrosion, and Wear Resistance of Al0.8CrFeCoNiCu0.5 High-Entropy Alloy

This study investigates the structure and corrosion behavior of the Al0.8CrFeCoNiCu0.5 high-entropy alloy prepared using non-consumable vacuum arc melting. XRD analysis identified BCC1 and BCC2 phases corresponding to (Fe-Cr) and Al-Ni, respectively, while the FCC phase aligned with Cu. SEM and EBSD observations confirmed an equiaxed grain structure with fishbone-like morphology at grain boundaries and modulated structures within the grains. The alloy exhibited minimal residual stress and strain. The alloy demonstrated a preferred orientation of grain growth along the <001> direction. Electrochemical testing in a 3.5% NaCl solution revealed a corrosion potential of −0.332 V and a corrosion current density of 2.61 × 10−6 A/cm2. The intergranular corrosion regions exhibited significant depletion of Al and Cu elements, with the corrosion products primarily consisting of Al and Cu. Al and Cu elements are susceptible to corrosion. The wear scar width of Al0.8CrFeCoNiCu0.5 high-entropy alloy is 1.65 mm, which is less than 45# steel, and high-entropy alloy has more excellent wear resistance. Given its unique attributes, this high-entropy alloy could find potential applications in high-end manufacturing industries such as the aerospace engineering, the defense industry, energy production, and chemical processing where high corrosion resistance and wear resilience are crucial.

Coupling effects of SiC and TiB2 particles on crack inhibition in Al-Zn-Mg-Cu alloy produced by laser powder bed fusion

A novel Al-Zn-Mg-Cu alloy free of cracks was produced utilizing laser powder bed fusion (LPBF) and modified with SiC and TiB2 particles. The interdependent effects of SiC and TiB2 particles on morphology, microstructure, and crystallographic texture were examined. The mechanisms behind phase evolution and crack inhibition were elucidated. The results show that a nearly dense Al-Zn-Mg-Cu alloy could be obtained when the mass fraction of SiC and TiB2 particles was 4%. TiB2 particles remained stable and acted as nucleation agents in the molten pool. Partial SiC particles reacted with the Al matrix to form rod-like Al4C3, lamellate Al4SiC4, and flocculent Si phases, which provided nucleation agents and liquid replenishment for matrix grains. The columnar grains of the matrix were refined into equiaxed grains, and the average size decreased from 37.15 μm to 7.54 μm. The preferential growth of grains along the (001) 〈001〉 direction was suppressed and transformed into a disordered random growth. The innovative Al-Zn-Mg-Cu alloy demonstrated an ultimate tensile strength of 492±12 MPa and an elongation of 7.2%±0.7%. The microhardness was enhanced, and the microhardness heterogeneity was reduced. The solidification properties were regulated, the temperature interval between solidus and liquidus was narrowed, and the liquidity of the molten pool was improved. The hot cracking of Al-Zn-Mg-Cu alloy was inhibited due to the interdependent effects of grain refinement by TiB2 particles and sufficient liquid metal replenishment by SiC particles.

Analysis of the formation mechanism of ceramic grains and mechanical properties of Mo2FeB2-based cermets by valence electron structure

The valence electron structures (VES) of Mo2FeB2-based cermets were constructed based on the empirical electron theory of solids and molecules (EET). The formation mechanism of grains and the influence of grain morphologies on the mechanical properties of the materials were explained in accordance with the calculated phase structure formation factors (S') and the interface electron structure (σN: the number of atom state groups, ∆ρ': electron density difference, and ρ': electron density), respectively. The results indicated that the morphologies of the Mo2FeB2 hard phase grains were reflected by the S' value of the distinct crystal planes. The progressive decrease in the Mo/B atomic ratio aggravated the differences between the S(210)' and S(001)' values and promoted the preferential growth of the hard phase grains along the [001] direction. This resulted in an increase in the (210)/(100) interface area, with the grains gradually forming an elongated structure. However, it was noticed that as the ratio of Mo to B increased, the value of |S(210)' − S(001)'| gradually tended toward 0, which allowed the elongated hard phase grains to transform into quasi-equiaxial grains. In addition, the maximum decrease in the σN value recorded was over 2500 when the Mo to B ratio increased continuously, indicating that the bonding strength at the (210)/(100) interface between the hard and binder phases was better at low Mo/B atomic ratios than at high Mo/B atomic ratios. This helped improve the fracture toughness and transverse rupture strength of the Mo2FeB2-based cermets.

Influence of local thermal cycle on the lattice and microstructure evolution of twin-wire directed energy deposition-arc fabricated equiatomic NiTi alloy

In the present work, the authors wish to investigate the effect of repeated heating cycles on the phase and crystal structure few layers at a time. Equiatomic NiTi alloy is additively manufactured using twin-wire directed energy deposition-arc (TW-DED-arc) in an in-situ alloying process from pure Ni and Ti wire feedstocks. The central region is wide enough for the extraction of several metallographic and tensile specimens away from dilution zones. Microstructure characterization reveals the incorporation of silicon preventing the formation of NiTi2 and the existence of two types of B2 austenite in the matrix, which has a composition of 50.2 at.%Ni-49.8 at.%Ti. The lattice is observed to dilate near the top regions under tensile thermal stress with no contribution from Ni-rich precipitates. Mechanical test gives a maximum ultimate tensile stress of 782.5 MPa with a fracture surface indicative of quasi-cleavage failure. The results show TW-DED-arc is able to produce fully dense, chemically homogenous NiTi alloys without detrimental phases. In addition, the local thermal cycles experienced by the samples gradually promote the nucleation of Ti5Si3 precipitates and lead to a preferential growth of NiTi grains along the (0 0 1) direction.

Analysis of Abnormal Texture and Strengthening Mechanisms of Extruded Mg–Gd–Y–Nd–Zr Alloy

The formation mechanism of an abnormal texture with <0001> orientation parallel to the extrusion direction (<0001>//ED) and strengthening mechanisms in the extruded Mg–Gd–Y–Nd–Zr alloy are investigated. When extruded at a ratio of 25, the abnormal texture is accompanied by a completely dynamic recrystallized (DRXed) microstructure, and its intensity increases with increasing extrusion temperature. When the extrusion ratio is reduced to 9, the multiple texture components are formed, accompanied by nonuniform microstructures. Rare‐earth (RE) elements segregating at the grain boundary or existing as a secondary phase affect the activation of nonbasal slips and preferential growth of DRXed grains. The formation mechanisms of abnormal texture are completed DRX, the operation of pyramidal <c + a> slip, and growth advantage. The strengthening mechanisms in the extruded Mg–Gd–Y–Nd–Zr alloy mainly include solid solution strengthening, grain boundary strengthening, and precipitate strengthening, among which solid solution strengthening plays a key role. The trade‐off between the three strengthening mechanisms results in the stability of the mechanical properties of the extruded Mg–Gd–Y–Nd–Zr alloy under various extrusion conditions.

Effect of pulsed laser energy on grain morphology and texture characteristics of stainless steel fabricated by laser-PTA additive manufacturing

This study proposes a pulse laser-assisted plasma transfer arc (Laser-PTA) additive manufacturing process. By using this process, the tensile strength and elongation of stainless steel are increased by 11.3% and 21.59% respectively. Using electron backscatter diffraction (EBSD) technique to study the microstructure and texture characteristics of the deposited layers. Further, the mechanism of the pulsed laser energy regulating the microstructure is revealed. The experimental results showed that the continuous growth of coarse columnar crystals in multi-layers deposition structures can be blocked by pulsed laser energy. Compared with the PTA process, the grain size of the multi-layers deposition structure obtained by the laser-PTA process is smaller, and the trend of preferred orientation is weakened. Moreover, increasing the laser pulse power can make this effect more significant. The result of texture analysis showed that the improvement of mechanical properties of laser-PTA samples is the result of grain refinement in deposition layers, inhibition of preferred orientation, and increase of volume fraction of high angle grain boundaries. The surface oscillation and thermal convection in the molten pool break the growth of columnar dendrites, destroy the original temperature gradient and affect the growth morphology and orientation of grains, which is the main mechanism to improve the process of laser-PTA additive manufacturing.

Realization of high piezoelectric performance in bismuth titanate niobate via B-site mixed-valance doping

Aurivillius-compound Bi3TiNbO9 (BTN) based high-temperature piezoelectric ceramics doped with mixed-valence cations (Mo1/3Cr2/3)4+ at the lattice B-sites, Bi3Ti1−x(Mo1/3Cr2/3)xNbO9 (BTN-MC100x, x = 0 −0.07), were prepared via the solid-state reaction method. The incorporation of the (Mo1/3Cr2/3)4+ ions into the BTN lattice promotes the preferential growth of grains along the a-axis, making it easier for polarization vector to flip. The optimized composition BTN-MC5 ceramic had a large d33 of 20.3 pC/N with a high TC of 901 °C. It was found that the donor doping effect of (Mo1/3Cr2/3)4+ and the formation of (CrTi′–VO⋅⋅–CrTi′)×defect dipoles contribute to reduce the concentration of oxygen vacancies, thus increasing the resistivity (2.2 ×105 Ω cm at 600 °C). In addition, the d33 of the BTN-MC5 ceramic exhibits an excellent thermal stability against depoling temperature Td. These findings indicate that the BTN-MC5 ceramic is promising candidate for the preparation of high-temperature piezoelectric sensors.

Evolution of grain size and texture of Zn-0.5Cu ECAP alloy during annealing at 200 ℃ and its impact on mechanical properties

Due to the low recrystallization temperature, the microstructure of wrought Zn alloys is naturally unstable, which affects their mechanical properties and limits their application. Therefore, it is crucial to elucidate the effect of microstructural evolution on mechanical properties of wrought Zn alloys. In this work, annealing treatment was performed on a Zn-0.5Cu (wt%) equal channel angular pressure (ECAP) alloy at 200 °C for different durations to investigate the microstructure evolution and its effect on the mechanical properties. An abnormal phenomenon that strength and ductility of the ECAP alloy decrease monotonically with increasing annealing time was observed, which is remarkably different from most other metallic alloys (Mg, Al, Cu, etc.). Detailed microstructure observations were conducted to unveil the mechanisms behind this abnormal phenomenon. Annealing for 1440 min induced not only an abnormal increase in texture intensity from 17.06 to 30.53 (which can be ascribed to preferential growth of high-texture grains with the<−12 to 10 >and<01–10 >components) but also a significant grain growth from 3.3 µm to 32.7 µm. Grain growth and dislocation annihilation resulted in the loss of strength, while the abnormal decrease in ductility during annealing was primarily due to texture enhancement and grain coarsening. The present work could provide guidance for the production and application of wrought Zn alloys in biomedical fields.

Abnormal texture formation and mechanical anisotropy of pre-aging extruded Mg-Gd-Y-Zn-Zr alloy with large-scale

In order to further explore the effect of pre-aging treatment on large-scale alloys, a pre-aging extruded Mg-9.32Gd-4.02Y-2.16Zn-0.48Zr (wt.%) alloy with large extrusion ratio (ER = 19.5) and extrusion temperature of 450 °C in large-scale (Φ308 mm × 800 mm) was investigated in this paper. It exhibited good properties and a more pronounced anisotropy. The comprehensive performance in the 45° direction was the best. The extrusion direction (ED) presented a high strength, while the transverse direction (TD) showed poor strength and ductility contemporaneously. The main results of strength anisotropy were the alignment orientation of the long-period stacking ordered (LPSO), fine grain strengthening, and texture strengthening. The c-axis of most of the grains in TD samples was perpendicular to the direction of applied stress because of the abnormal <0001>//ED texture, which reduced the ductility. In addition, the formation mechanism of abnormal texture has also been studied. The higher extrusion temperature reduced the critical shear stress (CRSS) of the non-basal slip system, and the higher strain promoted the rotation of the base plane along the principal stress axis under the operation of continuous non-basal slip, resulting in the abnormal <0001>//ED texture due to lattice rotation. On the other hand, dynamic recrystallization (DRX) also greatly affected the generation of the abnormal texture. Firstly, DRX produced a proportion of grains with a nucleation orientation of <0001>, then the subsequent preferential growth of DRX grains led to the vast majority of grains with an orientation tending towards <0001>. However, the former has less effect on abnormal texture than the latter.

Reduction effect of final-pass heavy reduction rolling on the texture development, tensile property and stretch formability of ZWK100 alloy plates

• ZWK100 alloy sheets with initial casting structures was fabricated by final-pass heavy reduction rolling (FHRR) up to 70% single reduction after single-pass rough rolling, and subsequent annealing causes a symmetrical ‘oblique-line split’ texture instead of the traditional ‘TD split’ texture. • The high rollability for 70% reduction was ascribed to the significant activity of the prismatic 〈 a〉 slip facilitated by the off-basal textures formed after rough rolling • The ‘oblique-line split’ texture was correlated with the preferred growth of grains with [ 1 ¯ 2 1 ¯ 1 ] - [ 1 ¯ 2 1 ¯ 2 ] //RD during annealing. • The FHRR-annealed ZWK100 sheets reveal quasi-planar isotropy in mechanical properties ( Δr 2 ∼0.1), large uniform-elongation of ∼35% and excellent stretch formability of 8.1. Obviously planar anisotropy due to ‘TD split’ orthotropic texture (TD indicates Transverse direction) always exist in the Rare-earth (RE) or Ca containing Mg alloy sheets, which is likely caused by the low-reduction rolling (and annealing) as revealed in our previous research. In this work, the as-cast billets of a ZWK100 alloy were subjected to final-pass heavy reduction rolling (FHRR) at 500 °C with different reductions (30%-70%) after rough rolling, aiming to investigate the reduction effect on the microstructure and texture formation. The results show that FHRR with higher reductions above 50% is in favor of shear banding formation but has little effect on the as-deformed texture components, and the excellent formability with single-pass reduction up to 70% is mainly ascribed to the activation of prismatic 〈 a〉 slip. FHRR with reduction above 50% and annealing can generate uniform grain structures of ∼10 μm and symmetrical ‘oblique-line split’ texture in (0001) pole figures, with basal poles tilting by about 50° from ND (Normal direction) towards some oblique-line of TD and RD (Rolling direction) as well as uniform distribution of counter lines as an annular shape, resulting in excellent elongation to failure of ∼50% and ultra-low planar anisotropy Δ r 2 of ∼0.1 and high stretch formability (Erichsen value: 8.1). The formation ‘oblique-line split’ texture in (0001) pole figures is mainly correlated with the preferred growth tendency of grains with [ 21 1 ¯ 1 ] - [ 12 1 ¯ 2 ] //RD, which was suggested to relate to the high mobility of some special boundaries such as 40°-45° [ 10 1 ¯ 0 ] (∑14). The influences of starting textures on the mechanical properties, planar anisotropy and related deformation modes, as well as their correlations with the stretch formability were comparatively investigated with the ‘TD split’ orthotropic texture as a counterpoint.

Wire arc additive manufacturing Al-5.0 Mg alloy: Microstructures and phase composition

Wire arc additive manufacture is well applied in the fabrication of Al-5.0 Mg products. The investigation of microstructure morphology and phase composition in different regions is not enough. Therefore, the factors of microstructure morphology, dislocations densities and phase composition are worthy to study. Investigations of microstructure morphology demonstrated that the cross-section along the deposition direction has diversified grain size and the diversity increases the dislocation density and decreases the residual stress. The preferred orientation of grain growth analyzed by XRD explained that the decreasing intensity of (200) could improve the homogeneity. EDS results revealed that Al and Al3Mg2 were the main phases. TEM results demonstrated that there was Al2Mg formed inside grains and the irregular shapes of precipitations. The temperature gradient in the two regions is the main factor causing the differences in dislocation density, precipitations formation and microstructure diversity

Realizing texture in bulk nanocrystalline Nd-Fe-B magnet via high-stress low-temperature rapid deformation

It is difficult to obtain nanoscale grain size and strong texture in hot-deformed magnets simultaneously, which is responsible for the low magnetic properties of nanocrystalline magnets. In this study, a strong texture was realized in a nanocrystalline Nd-Fe-B magnet via a high-stress low-temperature rapid deformation. Strong texture formation is ascribed to the high stress, which promotes the preferential growth of grains by increasing strain energy anisotropy. The nanocrystalline formation is ascribed to the low deformation temperature (below the melting point of the Nd-rich phase) and short deformation time. The effects of deformation temperature and applied stresses on the microstructure and magnetic properties were investigated in detail. Thus, the highest maximum energy product of 43.3 MGOe is obtained.

Influence of Plasma Surface Treatment of Polyimide on the Microstructure of Aluminum Thin Films

The effects of plasma treatment of polyimide substrates on the texture and grain size distribution of aluminum thin films were studied. Oxygen-argon plasma treatment increased the average grain size and enhanced the (111) film texture. For short oxygen-argon plasma treatment times, the deposited Al films showed a (111) texture with a bimodal grain structure and even a {111}&lt;112¯&gt; type in-plane texture. The preferential nucleation and grain growth of (111) grains are discussed in terms of the interface energy anisotropy.

Improving the isotropy and formability of extruded Mg-2Gd-1Zn (wt.%) alloy sheet by introducing an ellipse texture

In this work, a novel texture modification, termed the ellipse texture, is introduced by the pre-rolling and subsequent annealing (PRA) process in as-extruded (AE) Mg-Gd-Zn (GZ21) alloy. The static recrystallization (SRX) mechanisms and the evolution of microstructure during the PRA process are investigated by electron backscattered diffraction (EBSD), transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) techniques. The results show that the introduction of the ellipse texture distribution leads to the improved planar isotropy of the mechanical properties compared with the AE sheets, when tensile along different directions. Accordingly, the Erichsen value (IE value) increases to 5.7 ± 0.1 mm. Furthermore, the activation of non-basal dislocations (prismatic <a> and pyramidal <c+a> dislocations) during the pre-rolled process induces preferred nucleation sites for the SRX grains with the c-axis oriented to TD. The co-segregation of Gd and Zn atoms at grain boundaries leads to the preferred growth of these TD texture component grains. Both the preferred nucleation and growth of the SRX grains contribute to the formation of ellipse texture distribution in the PRA GZ21 alloys.