•The texture evolution of CuZr during ambient and cryogenic rolling was studied.•The mechanism of the texture transition induced by cryorolling was analyzed.•The cryorolling of CuZr alloys promotes the formation of brass-type shear bands.•The suppression of cross slip induces the Goss orientation in the remnant grains.The microstructure and texture evolution of the room temperature and cryogenically rolled Cu-0.3%Zr alloy were investigated at a range of true strains (0.36, 0.69, 1.20, 2.30) by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The high angle boundary spacing of lamellar grains along the normal direction is mainly dependent on the geometrical effect, and cryorolling has a minor refining effect on the width of the lamellae. However, the deformation twins and shear bands within the lamellar structure of the cryorolled CuZr alloy contribute to the grain refinement and improve the mechanical properties. The cryorolling enhances the inhomogeneous deformation and forms brass-type shear bands. In contrast to the copper-type texture in the room temperature rolled CuZr alloy, the cryorolled CuZr alloy exhibits a typical brass-type texture. This texture discrepancy is mainly attributed to the closely spaced twin/matrix lamellae and brass-type shear bands induced by cryorolling. The twin/matrix lamellae stimulate the initial formation of brass-type texture, and the shear bands promote its development. Unlike the room temperature rolled CuZr alloy, the Goss component is observed in the remnant grains in the cryorolled CuZr alloy. The occurrence of the Goss component may be attributed to the suppression of cross slip during cryorolling.

Cu-1Cr-0.1Zr (wt%) alloy strips were fabricated by a two-stage cryorolling and an intermediate aging treatment. The microstructures, mechanical/electrical properties and precipitation behaviors of the alloy were investigated. The results show that a desired combination of the tensile strength (690.13 MPa) and electrical conductivity (67% IACS) were obtained after the primary 30% thickness reduction and intermediate aging at 450 °C for 2 h followed by a secondary 60% thickness reduction at the cryogenic temperature. The improved strength can be attributed to the interactions of twin boundaries strengthening, grain boundaries strengthening, precipitation strengthening and strain hardening. For the alloy manufactured by cryorolling and intermediate aging treatment, the twin/matrix lamellar thickness decreases 38% and 55% compared with the alloy manufactured by cryorolling and room temperature rolling, respectively. In particular, results from energy-dispersive spectroscopy (EDS) mapping show that a core-shell structure with the shell of Zr and the core of Cr appeared after the intermediately aging treatment.

•Cu-TiB2 composites were in-situ synthesized by conventional casting method.•The grain size of the Cu-TiB2 composites was refined by the in situ TiB2 phase.•TiB2 significantly diminished the wear volume loss Cu-TiB2 composites.•TiB2 made an effective improvement on mechanical properties of Cu-TiB2 composites.In this work, TiB2 particulate reinforced copper matrix composites were fabricated by casting method, based on in situ precipitation reaction between B and Ti elements to form TiB2 particles in molten copper. The microstructures of the Cu-TiB2 composites were characterized using SEM and TEM. The results show that TiB2 particles are successfully formed in the copper matrix and the interfaces between these particles and the matrix are clean and well bonded. The friction and wear characteristics of the Cu-TiB2 composites were determined by carrying out dry sliding tests on pin-on-disk machine under varying loads, sliding speeds and sliding distances. A comparison between the volume wear losses of the composites under different conditions shows a significant improvement in wear property of the composites with respect to the pure copper. Furthermore, the mechanical properties of the composites with different TiB2 levels were also investigated. Both tensile strength and hardness are significantly improved with the increasing amount of TiB2 in copper matrix, while compromises of the elongation and electrical conductivity nevertheless occur in all cases.Download high-res image (492KB)Download full-size image

Three-dimensional morphology and formation process of icosahedral quasicrystal phase have been investigated in a melt-spun Al–18Mn alloy (in wt%). Three distinct layers corresponding to varying temperature gradient have been observed on the cross section of the ribbons. 3D morphologies of cellular and dendritic icosahedral phase have been obtained through electro-etching. A model has been proposed to describe the formation process of the icosahedral phase and α-Al during the rapid solidification. The icosahedral phases are primarily precipitated from the melt into fine cellular and dendritic particles, and subsequently engulfed by the α-Al which propagates in a planar morphology.