Single-crystal copper has received more and more attention in the important areas of the national economy due to its good electrical and thermal conductivity and elongation. Its low strength limits its application, and so strengthening methods for single-crystal copper are of great concern. Therefore, we study the strengthening and toughening mechanisms of single-crystal copper by equal-channel angular pressing (ECAP). The single-crystal copper was processed by ECAP using route A with a die (F = 105°, Y = 30°). The microstructure and texture evolution were investigated by EBSD, XRD and SEM. The tensile properties were also tested. The results show that the ECAP method can improve the strength of materials without decreasing the conductivity. Under low strain, the crystal orientation still maintains the original orientation characteristics. As the strain increases, it forms numerous deformation bands with the same direction as the matrix. The texture-transformation process is {111}<112> ® {111}<110> ® {110}<112> and {124}<211>. After 5 passes, the tensile strength increased from 168 MPa to 435 MPa, and the elongation declined from 63 % to 27.8 %. After 16 passes, the hardness increased from 60.4 HV to 125 HV, while the conductivity remained at a high level of 95 % IACS.Monokristalini~ni baker postaja zaradi svoje dobre elektri~ne in toplotne prevodnosti ter duktilnosti vse bolj popularen material na pomembnih podro~jih nacionalnih ekonomij. Zaradi nekoliko manj{e trdnosti je njegova uporabnost omejena.^e`elimo raz{iriti njegovo uporabnost, je razvoj novih metod njegovega utrjevanja zelo pomemben. Avtorji so raziskovali mehanizme utrjevanja in pove~evanja`ilavosti monokristalini~nega bakra s postopkom ECAP (iztiskovanjem pod kotom z enakim vhodom in izhodom matrice). Monokristalini~ni baker so obdelovali s postopkom ECAP z uporabo poti A, pri kateri ima orodje zunanji kot F =105°in notranji kot Y =30°. Razvoj mikrostrukture in teksture so raziskovali z EBSD, XRD in SEM. Prav tako so dolo~ili trdoto in mehanske lastnosti z nateznim preizkusom. Rezultati raziskav ka`ejo, da lahko postopek ECAP izbolj{a trdnost materiala brez poslab{anja prevodnosti. Pri majhnih deformacijah ostaja kristalna orientacija {e vedno nespremenjena. S pove~evanjem deformacije pa nastajajo {tevilni deformacijski pasovi z enako orientacijo, kot jo ima matrica. Proces pretvorbe teksture poteka v smeri {111}<112> ® {111}<110> ® {110}<112> in {124}<211>. Po 5 prehodih je natezna trdnost bakra narasla s 168 MPa na 435 MPa in raztezek je padel s 63,0 % na 27,8 %, elektri~na prevodnost pa je {e vedno ostala na visokem nivoju 95 % IACS. Klju~ne besede: monokristalini~ni baker, postopek ECAP (iztiskovanje pod kotom z enakim vhodom in izhodom matrice), tekstura, mehanske lastnosti
The evolutions of the microstructure and its effect on the mechanical and electrical conductivity properties of Cu1.5Cr0.1Si alloy after equal channel angle pressing (ECAP)-C path deformation and aging treatment have been investigated using scanning electron microscopy (SEM), x-ray diffraction (XRD), and electron back-scattered diffraction (EBSD). It was found that after the ECAP-C deformation at room temperature, with an extension of aging time, the strong (111) macro orientation formed in the Cu1.5Cr0.1Si alloy. The ultrafine crystals formed by ECAP and the rich chromium phase precipitated along grain boundaries during the aging process greatly improved the material strength. After aging at 350 °C for 4 h, the tensile strength, elongation, and conductivity reached 528 MPa, 15.27%, and 78.9% IACS, respectively. The fracture mode of the alloy was ductile fracture. The steady-oriented {111} <110> texture was beneficial to improving the conductivity of the material.
The actinide–halogen complexes (AnO2X4 2–, X = Cl, Br, and I) are the simplest and most representative compounds for studying the bonding nature of actinides with ligands. In this work, we attempted to synthesize the crystals of NpO2X4 2– (X = Cl, Br, and I). The crystals of NpO2Cl4 2– and NpO2Br4 2– were successfully synthesized, in which the structure of NpO2Br4 2– was obtained for the first time. The crystal of NpO2I4 2– could not be obtained due to the rapid reduction of Np(VI) to Np(V) by I–. The molecular structures of NpO2Cl4 2– and NpO2Br4 2– were characterized by single-crystal X-ray diffraction and infrared, Raman, and UV–Vis–NIR absorption spectroscopy. The complexes of NpO2X4 2– (X = Cl, Br, and I) were also investigated by density functional theory calculations, and the calculated vibration frequencies and absorption features were comparable to the experimental results. Both the experimental results and theoretical calculations demonstrate the strengthened Np–O bonds and the weakened Np–X bonds across the NpO2X4 2– series; however, the population analysis on the frontier molecular orbitals (MOs) of NpO2X4 2– indicates a slight reduction in the Np–O bonding covalency and an enhancement in the Np–X bonding covalency from NpO2Cl4 2– to NpO2I4 2–. Results in this work have enriched the crystal database of the AnO2X4 2– family and provided insights into the bonding nature in the actinide complexes with soft- and hard-donor ligands.
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