Microstructure Characteristics,Texture Evolution and Mechanical Properties of Al-Mg-Si-Mn-xCu Alloys via Extrusion and Heat Treatment

In this work,the impact of extrusion and post-extrusion heat treatment(T6)on the microstructure and mechanical properties of the Al-1.2Mg-0.8Si-0.5Mn alloy with different Cu contents(0,0.6,1.3 and 2.0 wt%)was studied.Microstructure characterization showed that all extruded alloys exhibited elongated grain structure with an average grain size of~4.8μm.The dominant texture components were deformation texture(A*,Copper and P texture),while the proportion of random texture initially increased and then decreased with increasing Cu content.After T6 treatment,the grain size of the four alloys increased significantly,but the growth trend decreased with increasing Cu content,and the textures transformed into recrystallized textures(Cube,A and Goss texture).Tensile testing revealed that the designed T6 alloys with 2.0%Cu content exhibited an excellent strength-ductility balance,i.e.,a yield strength of 342.9 MPa,an ultimate tensile strength of 424.8 MPa and an elongation of 15.9%.The enhanced strength was mainly attributed to fine grain strengthening,solid solution strengthening and aging strengthening mechanisms.The superior ductility was due to the pinning effect of fine precipitates and high dislocation accommodation capacity caused by heat treatment.

Effect of Base Material on Microstructure and Texture Evolution of a Ti–6Al–4V Electron-Beam Welded Joint

The effect of base material（BM） on microstructure and crystallographic orientation evolution of a Ti–6Al–4V electron-beam welded joint was investigated. Meanwhile, the crystallographic orientation of prior b grains was studied by advanced electron backscattered diffraction data processing. The inhomogeneity of microstructure within welded joint was formed due to the different microstructures of BM. By comparing microstructure details of the welded joint, including microstructure morphology and crystallographic orientation with those of the base material, it can be found that both the microstructure morphology and crystallographic orientation of the EBW joint would be controlled by BM.

Evolution of microstructure and texture in copper during repetitive extrusion-upsetting and subsequent annealing

The evolution of the microstructure and texture in copper has been studied during repetitive extrusionupsetting（REU） to a total von Mises strain of 4.7 and during subsequent annealing at different temperatures. It is found that the texture is significantly altered by each deformation pass. A duplex 001 ＋ 111 fiber texture with an increased 111 component is observed after each extrusion pass,whereas the 110 fiber component dominates the texture after each upsetting pass. During REU, the microstructure is refined by deformation-induced boundaries. The average cell size after a total strain of 4.7 is measured to be ~0.3 μm. This refined microstructure is unstable at room temperature as is evident from the presence of a small number of recrystallized grains in the deformed matrix. Pronounced recrystallization took place during annealing at 200？C for 1 h with recrystallized grains developing predominantly in high misorientation regions. At 350？C the microstructure is fully recrystallized with an average grain size of only 2.3 μm and a very weak crystallographic texture. This REU-processed and subsequently annealed material is considered to be potentially suitable for using as a material for sputtering targets.

Characterizing microstructure and texture after recrystallization annealing of Hi-B steel with simutaneous decarburization and nitriding

How to manufacture the high magnetic induction grain-oriented silicon steel（Hi-B steel）by the process featured with the primary recrystallization annealing was demonstrated,during which nitriding and decarburizing were simultaneously realized in laboratory.By the techniques of optical microscope,scanning electronic microscope and electron backscattered diffraction,both the microstructure and the texture in the samples were characterized.The samples had been subjected to nitriding to different nitrogen contents at two specified temperatures using the two defined microstructural parameters：the grain size inhomogeneity factorσ＊and the texture factor AR.The former is the ratio of the mean value to standard deviation of grain sizes;the latter is the ratio of the total volume fraction of the harmful textures to that of beneficial textures including {110}〈001〉.When the N content increased from 0.0055%to 0.0330%after the annealing at both 835 and 875°C,the resultant recrystallized grain size decreased butσ＊changed little;whilst the rise of annealing temperature from 835 to 875°C resulted in the increase in both grain size andσ＊.Moreover,either the injected N content or temperature had insignificant influence on the components of primary recrystallization texture developed during annealing.However,the increase of temperature led to the decreases in both intensity and volume fraction of{001}〈120〉and{110}〈001〉textures but increases in the{114}〈481〉andγfiber textures and the resultant decrease of AR.

Enhanced thermoelectric performance of n-type Bi_(2)Te_(2.7)Se_(0.3) via a simple liquid-assisted shear exfoliation

A liquid-assisted shear exfoliation (LASE) as a new powder metallurgy method coupled with spark plasmasintering (SPS) was applied for n-type Bi_(2)Te_(2.7)Se_(0.3) and the effects on microstructure and anisotropictransport properties were investigated. Results revealed an effective reduction of average grain size dueto LASE and a high texturing in the bulks. Moreover, along the in-plane direction, electrical conductivitywas increased noticeably due to an enhanced carrier concentration, leading to a significantly improvedpower factor of 25 μW cm^(–1) K^(–2) at 303 K. Meanwhile, the total thermal conductivity was reduced effectively owing to reduction both in lattice component due to enhanced phonon scattering with the grainsize reduction, and in the bipolar component inhibited by the increased carrier concentration. Ultimately,a peak thermoelectric figure of merit (ZT) value of 0.83 was obtained at 448 K along the in-plane direction, increased by 95% compared with the pristine one. These results demonstrate the LASE process as auseful assistant method for enhancing the TE performance of layered materials.