Resistometric investigation on effect of Cu addition on 473 K aging behavior of Al-1%Mg2Si alloys.

Abstract

ABE , Shin-ya KOMATSU  Masahiko IKEDA and Takeo SAKURAI   Al 1Mg 2 Si 0,  0.17,  0.43,  0.72Cu alloys were solution treated for 3.6 ks at 848 K, water quenched and aged at 473 K. Behavior of added Cu during these heat treatments and eŠect of the Cu on age-hardening were investigated by resistometry and tensile test with assist of transmission electron microscopy. The resistivity in as water quenched state well coincides with the value calculated from 0.023 massFe, the equilibrium solubility at 848 K in Al Fe binary system, and all of other elements in solution. Moreover, the resistivity increases linearly with amount of the added Cu. Namely all of the added Cu is dissolved in the as quenched state. By Cu addition, the initial agehardening rate at 473 K aging is increased and the softening with over-aging is suppressed. Though the Cu addition increases proof stress at peak age-hardening, it also decreases the resistivity decrement from the as quenched state caused by the aging. This discrepancy, that the small total amount of precipitates, which is suggested from small decrement of resistivity by the peak aging, gives the larger age-hardening, can be explained by the decrease in average length with Cu addition which may be directly related to the increase in number of needle shaped precipitates per unit area.

Cu Segregation around Metastable Phase in Al-Mg-Si Alloy with Cu

“…18) This precipitate may cause this behavior during quenching, because the added Cu for an Al-1.0 mass% Mg 2 Si alloy can be obtained as 0.17-0.72 mass% at 848 K, which is the same temperature of the present solution heat treatment. 19) According to Wolverton's result by a first-principles total energy method, the fcc-based formation enthalpies with special quasi-random structures, ÁH fcc SQS , for Cu-Mg and MgSi have been calculated as À2:6 and À16: 4. 20) As the value of Cu-Mg is smaller than that of Mg-Si, formation of Cu-Mg clusters as shown in Fig.…”

Solar Neutrino Results from Super-Kamiokande

“…The water transparency (WT) in the MC simulation is defined using absorption and scattering coefficients as a function of wavelength (see [10] for details). The dominant contribution to the variation of the WT is a variation in the absorption length.…”

“…Due to the precise control of the input water temperature, the convection inside the tank is minimized everywhere but the bottom, below z = −11 m. Due to a small amount of convection in the bottom of the tank and a constant rising temperature above, the absorption coefficient is modeled as a constant below z = −11 m and with a linear function above this height. This "top-bottom" asymmetry of the WT is determined by studying the distribution of hits coming from a Ni-Cf gamma-ray source (see [10]) in the "top", "bottom" and "barrel" regions of the detector. It is found that the hit rate of the top region of the detector is 3 ∼ 5% lower than that of the bottom region.…”

“…It is found that the hit rate of the top region of the detector is 3 ∼ 5% lower than that of the bottom region. The time dependence of this top-bottom asymmetry is monitored using the same Ni calibration, as well as an auto-xenon calibration [10]. The introduction of this time dependent absorption coefficient has much reduced the systematic uncertainty resulting from the directional dependence of the energy scale, especially useful for the solar neutrino day-night asymmetry analysis.…”

Light Quark Fragmentation in Polarized Z{sup 0} Decays at SLD

“…reconstructing emission angles of individual Cherenkov photons radiated by charged particles passing through liquid and gas radiator systems of the SLD Cherenkov Ring Imaging Detector (CRID) [2]. In each momentum bin, identified π, K, and p were counted, and these were unfolded using the inverse of an identification efficiency matrix [3], and corrected for track reconstruction efficiency.…”