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Evolutions of texture and lattice strain of swaged brass samples were investigated by neutron diffraction at STRESS-SPEC under tensile deformation using a unique tension/compression rig. The two phased sample BS1 (61% α-brass and 39% β-brass) became 100% α-brass after 400 °C annealing (sample BS2). The starting texture of the as-received material BS1 was the typical , double fiber. This texture develops firstly by in-situ tension to a moderate strengthening. After annealing (BS2) the fiber survives with surprisingly high strength and develops by in-situ tension a very strong fiber of 39 mrd. Line broadening and lattice strain behaviour shows the development of the elastic strain and plastic strain.

A Fe - 25 at% Co - 9 at% Mo alloy can be hardened by nm-sized (Fe, Co)7Mo6 µ-phase precipitates which is accomplished by solution annealing in the austenite region followed by rapid quenching to room temperature and subsequent aging below the austenite transition temperature. In overaged condition the Mo-content in the remaining matrix drops towards zero and, therefore, the matrix consist of 71 at% Fe and 29 at% Co. The binary Fe-Co system shows a disorder-order, A2↔B2 transition at a critical ordering temperature between 25 at% and 72 at% Co. It is expected that the remaining matrix of an overaged Fe - 25 at% Co - 9 at% Mo alloy also exhibits such an ordering reaction. It will be demonstrated that the formation of a B2 ordered FeCo phase can be delayed or completely prevented by rapid quenching from temperatures above the critical ordering temperature. This has a strong impact on the mechanical properties of this alloy which have been studied by means of tensile, impact toughness and hardness testing. The evidence for a disorder-order transition in this alloy has been given by neutron diffraction as well as high resolution transmission electron microscopy.

Microstructure and texture evolutions during tensile and compression deformation of an as-extruded Mg–11Gd–4.5Y–1Nd–1.5Zn–0.5Zr (wt%) alloy have been investigated using in-situ synchrotron radiation diffraction and subsequent microscopy. The alloy consists of 〈View the MathML source101¯0〉 fiber texture, {View the MathML source112¯0}[0001] and {View the MathML source112¯0}〈View the MathML source101¯0〉 texture components prior to deformation. The texture evolves from [0001] to 〈View the MathML source101¯0〉 in tension, but from 〈View the MathML source101¯0〉 to [0001] in compression. The evolution of texture is attributed to the activity of the tensile twinning and non-basal 〈a〉 type slip. The tendency of texture evolution depends on the favorable texture component for the activation of above deformation modes. The grain refinement, Mg5(Gd, Y, Nd) and LPSO phases, and the texture contribute to the improvement in strength. The authors thank Dr. Jan Bohlenand Dr. Sangbong Yi for their fruitful discussion. Prof. Florian Pyczak and Mr. Uwe Lorenzare acknowledged for the provision of access to the TEM facilities at Helmholtz-Zentrum Geesthacht. The access to the beam line PETRA III at DESY, Hamburg, Germany was provided under the proposal number I-20130153,andtheworkofN. Schellis greatly appreciated. This work is supported by the National Key Technologies R&D Program(2012BAE01B04,2012DFH50100,KGFZD-125-13-021,201001C0104669453). Zijian Yu would like to thank the Chinese Academy of Sciences and German Academic Exchange Service (CAS-DAAD)scholarship program (Grant Number: A/12/94735)for the financial support.

An interfacial CNT-(Mg-6Zn) layer was introduced between SiC particle and Mg-6Zn matrix by a novel method in aim to reduce the excessive thermal residual stresses between SiC particles and matrix. The CNTs were synthesized via CVD on the SiC surfaces, and CNTs kept on the surfaces of SiC particles in the composite during fabrication process. The influence of the interfacial CNT-(Mg-6Zn) layer on the microstructure, the mechanical properties and the Type II thermal residual stresses of composite were investigated with neutron diffraction method. Compared with mono-SiCp reinforced Mg-6Zn composite, the CNTs@SiCp/Mg-6Zn composite presents superior mechanical properties. The E, YTS, UTS and elongation are increased by 9.6%, 14%, 20%, 18.2% respectively. The residual stress of Mg in CNTs@SiCp/Mg-6Zn (35 MPa) is less than half of that (74 MPa) in SiCp/Mg-6Zn composite. Digital image correlation (DIC) investigation indicates that the additional CNTs enhances the bonding strength between SiCp and Mg matrix. The interface layer could release the thermal residual stresses in the composite in two ways: firstly, the gap of the coefficient of thermal expansion (CTE) between the SiCp and the Mg matrix is reduced; secondly, the thermal diffusivity of the composite is declined, leading to lower cooling rate of the as-cast composite in which a portion of residual stresses are released. This work highlights the influence of the interfacial CNT-(Mg-6Zn) layer on the Type II residual stresses and the mechanical properties of the CNTs@SiCp/Mg-6Zn composite.

Ni–Mn–Ga single crystal alloys can exhibit giant magnetic shape memory effect through variant reorientation induced by the magnetic field. However, such effect is greatly weakened in polycrystalline alloys, due to the orientation differences of martensite variants and the constraints of grain boundaries. Here, to improve the magnetic shape memory effect, a polycrystalline Ni50Mn28.5Ga21.5 alloy with coarse columnar shaped grains and strong A texture is prepared by directional solidification. With the aids of mechanical training, the twinning stress of five-layered modulated (5 M) martensite in the directionally solidified Ni50Mn28.5Ga21.5 alloy is successfully lowered to ~0.9 MPa. A giant magnetic field induced strain up to ~2.1% is achieved under the magnetic field of 1 T, being much higher than those reported previously in polycrystalline alloys. In addition, a reversible magnetostrain of ~0.4% is also attained without the assistance of an external stress or a magnetic field. It is demonstrated that the microstructure control through directional solidification as well as mechanical training could be an effective solution to enhance the magnetic field induced output strain in polycrystalline Ni–Mn-Ga alloys.

The present work studies the effects of solid solution Gd on the texture and lattice strain evolution of an extruded Mg15Gd alloy under uniaxial compression. In situ experiments were carried out using high energy X-ray diffraction on samples of the investigated materials with three different orientations. The original textures of the pure Mg and the Mg15Gd alloy exhibit basal planes that are preferentially parallel and perpendicular to the extrusion direction (ED), respectively. The c/a ratio of the Mg15Gd alloy decreases with increasing Gd content in the solid solution, leading to a different deformation behavior compared with pure Mg under the compressive load. The addition of Gd enhances the slip and twinning modes. However, prismatic slip is activated earlier in the Mg15Gd alloy due to the lower c/a ratio.

The work hardening and softening behavior of pure Mg influenced by Zn addition were studied through the neutron diffraction at STRESS-SPEC under in-situ tensile deformation. The measurement of the line broadening evolution during in-situ tension was used to study the variation of dislocation density in pure Mg and Mg–5Zn alloy, which revealed the effect of dislocation on work hardening behavior. Meanwhile, the tensile stress reduction (△Pi(i=1,2,3)) due to the softening effect at different in-situ tensile deformation stages were calculated to analyze the effect of Zn addition on softening behavior. The results show that the work hardening rate of pure Mg is larger than that of Mg–5Zn alloy in the early stage of deformation because of the stronger effect of grain size on the work hardening behavior. But the work hardening rate of Mg–5Zn alloy is higher than that of pure Mg in the later stage of deformaiton, which is attributed to the stronger effect of precipitates on work hardening behavior. Moreover, △P1 of pure Mg is larger than that of Mg–5Zn alloy, which was explained by the large grain size of pure Mg results in higher stored energy during the early deformation stage, and providing a greater driving force for the softening behavior. However, with the increase of tensile strain, the increase significantly of the stored energy in Mg–5Zn alloy due to the dislocations migration hindered by precipitates during the tensile deformation, leading to a higher driving force for softening behavior in the later deformation stage. Thus, △P3 of Mg–5Zn alloy is larger than that of pure Mg.

In present work, the ductile Mg–Zn–Y alloy (ZW31) was introduced into the 10 μm 15 vol% SiCp/AZ91 composites (PMMCs) to coordinate the deformation of PMMCs during the rolling process, then the ZW31/PMMCs laminate with the thickness of ~1 mm was prepared successfully. The microstructure and mechanical properties of the as-rolled ZW31/PMMCs laminate before and after the annealing process was investigated, the results indicated that existence of ZW31 alloy layer can absorb energy and relieve stress concentration of PMMCs layer by the formation of twins, which not only break through the bottlenecks of poor toughness of PMMCs, but also make it possible for the rolling of PMMCs sheet. The recrystallization behavior of the ZW31 alloy layer and PMMCs layer was completely different during the subsequent annealing process. For the ZW31 alloy layer, recrystallization induced by twinning, while the recrystallization in PMMCs layer related to the introduced particle. The typical rolling texture was formed in the ZW31/PMMCs laminate, and the intensity of which was mainly controlled by the ZW31 alloy. Application of annealing process improved the elongation of the ZW31/PMMCs laminate, however, at the expense of strength. Cracks originate in different positions of PMMCS layer and then connect with each other along the direction which perpendicular to the stress. The existence of ZW31 alloy layer inhibits the propagation of crack and is propitious to improve the ductility of ZW31/PMMCs laminate.

The compressive deformation behavior at elevated temperature of the as-extruded and as-ECAPed Mg-5.3Zn-0.6Ca (wt%) alloys was investigated in the current study. The flow stress in the as-ECAPed alloy was lower than that of the as-extruded alloy when the compressive temperature was above 200 degrees C, due to the grain boundary softening effect. The strain rate sensitivity (SRS) was remarkably enhanced with the decrease of grain size or the increase of test temperature, and the corresponding m-value was calculated as 0.06-0.13, which indicated that the deformation was mainly dominated by the climb-controlled dislocation creep. Furthermore, the grain boundary sliding (GBS) mechanism might also be activated, which contributed to the higher SRS in the as-ECAPed alloy. The true deformation activation energy (Q') modified by threshold stress was calculated as 92-98 and 70-76 kJ/mol in the as-extruded and as-ECAPed alloy, respectively, which was close to the activation energy for grain boundary diffusion, and the lower Q'-value in the as-ECAPed alloy might be derived from the non-equilibrium grain boundaries. (C) 2013 Elsevier B.V. All rights reserved.

In this paper, three kinds of magnesium matrix composites reinforced by SiCp with the sizes of 0.2, 5 and 10 μm, respectively, were fabricated by stir casting technology. Then the as-cast ingots were deformed by the combination of forging and extrusion process. Typical microstructures were obtained in the composites reinforced by different particle sizes. For the composites with lower volume fraction of particles (2%), submicron SiCp had significant influence on grain refinement and strengthening effect, which resulted in better mechanical properties of submicron SiCp/AZ91 composite. However, mechanical properties reduced owing to the obvious agglomerated submicron SiC particles as the volume fraction increased to 5% and 10%. On the contrary, for micron SiCp/AZ91 composite, the grain size was refined and the strengthening effect was enhanced with the increasing of volume fraction. Although particle size has no influence on the texture type, it has different effects on weakening the intensity of texture.

The effect of trace Mn addition on the microstructure, texture and mechanical properties of the as-cast and as-extruded Mg–5.25 wt.% Zn–0.6 wt.% Ca (ZX51) alloys was investigated in this study. Mn addition had a negligible effect on the grain size of the as-cast ZX51 alloy. However, the addition of Mn led to the obvious decrease of grain size in the as-extruded Mg–5.25 wt.% Zn–0.6 wt.% Ca–0.3 wt.% Mn (ZXM510) alloy, because the Mn addition restricted the grain growth during the hot extrusion process. After the addition of Mn, the basal fiber texture with most of {0 0 0 2} planes parallel to the extrusion direction (ED) was significantly enhanced in the as-extruded ZXM510 alloy. Both tensile yield strength (TYS) and ultimate tensile strength (UTS) were increased in the as-extruded ZXM510 alloy, while the ductility was slightly decreased, which was ascribed to the grain refinement and texture strengthening.

In the present study, 10 vol.% SiCp/AZ91 magnesium matrix composites are fabricated by stir casting. The as-cast ingots are cut into cylindrical billets, and then forged at 420 °C with different deformation amounts (40, 50, 60 and 80%) at a constant RAM speed of 15 mm/s. The results illustrate that the addition of SiC particles has significant influence on refining grain size and improving tensile strength of AZ91 matrix, however, weakening basal plane texture. After forging SiCp/AZ91 composites, the intensity of basal plane texture increases as deformation amount increases. The grain size of composite matrix grows up slightly as the deformation amount increased to 60%, and then it was refined obviously as the deformation amount continues to increase to 80%. The smaller deformation amount is propitious to improve particle distribution, while lager deformation amount promotes SiC particle agglomeration. Thus, the tensile strength increases as the deformation amount increases to 50%, however, it decreases as the deformation amount continues to increase to 80%.

The pure Mg sheets were processed by ARB at 400 °C and 300 °C up to 8 cycles and 4 cycles, respectively. The microstructure was refined during the first cycle and only homogenized during the following ARB process due to the high deformation temperature, intermediate reheating and air-cooling. The ARB process did not show an obvious effect on the tensile properties of the as-ARBed pure Mg sheet due to the stable grain size and dominant basal plane texture during ARB. Further deformation should be introduced to improve the bonding quality of the as-ARBed sheet.

The Mg/Al laminated composite was fabricated by the accumulative roll bonding (ARB) using the pure magnesium and Al5052 alloy at 400 °C. Tensile properties along rolling direction and the transverse direction and the microhardness were evaluated at the ambient temperature. The tensile strength of the laminated Mg/Al composite along both directions increased gradually till two ARB cycles, but then decreased after the third ARB cycles. Optical microscopy and scanning electron microscopy (SEM) were utilized to reveal the microstructure evolution and the failure mechanism. Grain refinement of Mg layers was not obvious during the ARB process due to the high temperature and interval reheating. The obvious crack at the coarse intermetallic compounds and rupture of the Al layer after the third cycle led to the premature failure of the sample along the rolling direction during the tensile test.

SiCp/AZ91 magnesium matrix composite was fabricated by stir casting. The as-cast ingots were cut into cylindrical billets, and then forged at different temperatures (320, 370, 420, 470 and 520 °C) at a constant RAM speed of 15 mm/s with 50% reduction. The microstructure evolution of the composites during forging was investigated by optical microscope, scanning electron microscope, and transmission electron microscope. The texture of the forged composites was measured by neutron diffraction. Mechanical properties of the composite at different forging temperatures were tested by tensile tests at room temperature. It was found that a strong basal plane texture formed during forging, and the intensity of basal plane texture weakened as forging temperatures increased. The particle distribution in the composite was significantly improved by hot forging. Typical microstructures were obtained after forging at different temperatures and the composite with different microstructures offered different mechanical properties during tensile test.

Equal channel angular pressing (ECAP) of the in situ Mg2Si reinforced Mg composite was performed with route Bc up to 8 passes using a 90° die. Refinement and re-distribution of the reinforced phase Mg2Si was investigated. Bulk texture development during ECAP was characterized by neutron radiation. Results showed that only the eutectic Mg2Si (Type-II) was proposed to be effective for preparing the in situ Mg2Si/Mg composite. Neutrons texture analysis briefly illustrated that a 〈00.2〉 basal fiber with the obtainment of less shear effect was formed. But the asymmetry of basal fiber around the ECAP direction was also observed. Both uniform texture and homogeneity distribution of Mg2Si particles played an important role in the tensile behavior of ECAPed composite.