Wang Y.Q.,Beijing University of Technology |
Huang H.,Beijing University of Technology |
Wen S.P.,Beijing University of Technology |
Gao K.Y.,Beijing University of Technology |
And 5 more authors.
Materials Science Forum | Year: 2015
The effects of the homogenization conditions on the microstructure of Al-Zn-Mg-Cu-Zr-0.5Er alloy were investigated by differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). The results showed that a lot of coarse phases existed in as-cast Al-Zn-Mg-Cu-Zr-0.5Er alloy. The dissolvable phases at grain boundary consisted of Mg32 (Al, Zn)49. The residual phases dissolved into the matrix gradually during homogenization with increasing temperature and prolonging holding time. When the temperature increased to 465°C, and time prolongs to 24h, the main phase disappeared except the Fe and Er enriched phase, as a result of its high melting temperature. Taking into account the precipitation of Al3Er, we used a two-step homogenization. Hence, the optimum parameters of homogenization were 400 °C for 4 h and 465 °C for 24 h, which are good for the presence of coherent, elastically hard and nano-sized Al3(Er, Zr) particles and the dissolvable coarse phases. © (2015) Trans Tech Publications, Switzerland.
Bai Q.,University of Science and Technology Beijing |
Li H.,University of Science and Technology Beijing |
Xiang S.,Southwest Aluminum CO. |
Wang Z.,Southwest Aluminum CO. |
And 3 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2014
The effects of casting parameters on casting process of AA7050 alloy were investigated by coupling thermal, fluid flow and stress fields based on the parameters provided by an aluminum corporation. The results show that the casting speed has a prominent effect on stress field while the influences of casting temperature and water flow rate are not obvious. The optimization of casting parameters was performed through numerical simulation in order to solve hot tearing problem in 800 mm round billets. Copyright © 2014, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved
Huang W.,General Research Institute for Nonferrous Metals, China |
Li X.,General Research Institute for Nonferrous Metals, China |
Zhang K.,General Research Institute for Nonferrous Metals, China |
Li Y.,General Research Institute for Nonferrous Metals, China |
And 2 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2012
The microstructure evolution and composition of EW75 cast and homogenized alloy were studied by optical microscopy, scanning electron microcopy, energy dispersive spectrometer, to study the high temperature diffusion of rare earth elements in EW75 alloy. The results showed that serious dendrite segregation existed in the EW75 alloy ingot, and many non-equilibrium solidification eutectics enriched in the grain boundary. Gd, Y, Nd, elements distributed unevenly from the grain boundary to the side of the alloy, large as-cast organizations with skeletal shape were constituted by α-Mg, Mg 24Y 5, Mg 5Gd and Mg 41Nd 5, and the grain size of as-cast alloy was about 100 μm. Many eutectics still exited in the grain boundary after HTT at 505, 520°C for 24 h as the temperature was too low. Most of the non-equilibrium eutectic phases dissolved after high temperature treatment (HTT) at 535°C for 20 h, and all elements became more homogenized, but the grain size became large. The concentration distribution of all elements which distributed regularly were studied by EDS, and the relation curves of lnδ-t for Gd, Y, Nd in different temperature were calculated by using kinetic equation. Diffusion parameters were obtained by linear fitting finally.