title: Experimental study of the Ca-Mg-Zn system using diffusion couples and key alloys.
abstract: Nine diffusion couples and 32 key samples were prepared to map the phase diagram of the Ca-Mg-Zn system. Phase relations and solubility limits were determined for binary and ternary compounds using scanning electron microscopy, electron probe microanalysis and x-ray diffraction (XRD). The crystal structure of the ternary compounds was studied by XRD and electron backscatter diffraction. Four ternary intermetallic (IM) compounds were identified in this system: Ca3MgxZn15-x(4.6 ⩽x⩽ 12 at 335 °C, IM1), Ca14.5Mg15.8Zn69.7(IM2), Ca2Mg5Zn13(IM3) and Ca1.5Mg55.3Zn43.2(IM4). Three binary compounds were found to have extended solid solubility into ternary systems: CaZn11, CaZn13and Mg2Ca form substitutional solid solutions where Mg substitutes for Zn atoms in the first two compounds, and Zn substitutes for both Ca and Mg atoms in Mg2Ca. The isothermal section of the Ca-Mg-Zn phase diagram at 335 °C was constructed on the basis of the obtained experimental results. The morphologies of the diffusion couples in the Ca-Mg-Zn phase diagram at 335 °C were studied. Depending on the terminal compositions of the diffusion couples, the two-phase regions in the diffusion zone have either a tooth-like morphology or contain a matrix phase with isolated and/or dendritic precipitates.
authors.affiliation: Department of Mechanical Engineering, Concordia University, 1455 de Maisonneuve Blvd W, Montreal, Quebec, H3G 1M8, Canada.
authors.forename: Yi-Nan
authors.initials: YN
authors.lastname: Zhang
authors.affiliation: Department of Mechanical Engineering, Concordia University, 1455 de Maisonneuve Blvd W, Montreal, Quebec, H3G 1M8, Canada.
authors.forename: Dmytro
authors.initials: D
authors.lastname: Kevorkov
authors.affiliation: Department of Mechanical Engineering, Ecole de technologie superieure, 1100 rue Notre-Dame Ouest, Montreal, Quebec, H3C 1K3, Canada.
authors.forename: Florent
authors.initials: F
authors.lastname: Bridier
authors.affiliation: Department of Mechanical Engineering, Concordia University, 1455 de Maisonneuve Blvd W, Montreal, Quebec, H3G 1M8, Canada.
authors.forename: Mamoun
authors.initials: M
authors.lastname: Medraj
keywords: Ca–Mg–Zn; diffraction; diffusion; electron microprobe; phase diagrams