Phase equilibria of the Mg-Sn-Ag system in Mg-rich corner at 320 and 400℃ were experimentally investigated with nine ternary alloys subjected to electron probe microanalysis and X-ray diffraction techniques.No ternar...Phase equilibria of the Mg-Sn-Ag system in Mg-rich corner at 320 and 400℃ were experimentally investigated with nine ternary alloys subjected to electron probe microanalysis and X-ray diffraction techniques.No ternary compounds were observed at both isothermal sections.Two three-phase triangles,i.e.hcp(Mg)+Mg_(2)Sn+Mg_(3)Ag and Mg_(2)Sn+Mg_(3)Ag+MgAg(bcc_B2),were both observed at 320 and 400℃.A new three-phase region of Ag3Sn+Mg2Sn+MgAg(bcc_B2)was additionally observed at 320℃,which implied that the binary phase Ag3Sn has a considerable solubility of Mg in the ternary system at the temperature.And the maximal solubility of Mg in Ag3Sn was measured to be 27.2 at.%.This result is not consistent with the thermodynamic calculated isothermal section at 350℃ from Wang et al.[11]and put forward a new requirement or refinement for the optimization of the Mg-Sn-Ag ternary system.At 400℃,the maximal solubility of Sn in the Mg3Ag phase was determined to be about 3.0 at.%Sn,and the solubility of Ag in Mg2Sn was negligible.The temperature of ternary eutectic reaction at Mg-rich corner(L↔hcp(Mg)+Mg_(54)Ag_(17)+Mg_(2)Sn)was measured by differential scanning calorimetry.The partial isothermal sections in Mg-rich corner of the ternary system at 320 and 400℃ were then constructed based on the above experimental data.展开更多
Microstructure and mechanical properties of a new high-strength Mg–6 Zn–4 Al–1 Sn alloy were investigated. Microstructure of the as-cast Mg alloy exhibited partially divorced characteristics. The dendritic structur...Microstructure and mechanical properties of a new high-strength Mg–6 Zn–4 Al–1 Sn alloy were investigated. Microstructure of the as-cast Mg alloy exhibited partially divorced characteristics. The dendritic structure of the Mg–6 Zn–4 Al alloy was significantly refined with the addition of 1%（in weight） Sn, but Mg2 Sn phases were not formed. In addition, an icosahedral quasi-crystal phase was formed in the as-cast Mg–6 Zn–4 Al–1 Sn alloy. It was found that after the double-aging treatment through two different heat treatments on the Mg–6 Zn–4 Al–1 Sn alloy, the precipitates were finer and far more densely dispersed in the matrix compared with single-aged counterpart, resulting in a significant improvement in tensile strength with yield strength, ultimate tensile strength and elongation of 175 MPa, 335 MPa and 11%,respectively.展开更多
Effects of additions of trace Sn on the bake-hardening responses of a pre-aged Al-0.85 Mg-0.85 Si(in wt%)alloy were investigated through mechanical tests,differential scanning calorimetry,electrical resistivity and tr...Effects of additions of trace Sn on the bake-hardening responses of a pre-aged Al-0.85 Mg-0.85 Si(in wt%)alloy were investigated through mechanical tests,differential scanning calorimetry,electrical resistivity and transmission electron microscopy.Results indicate that trace Sn additions reduced the number density of pre-aging clusters by inhibiting the formation of unstable counterpart during pre-aging treatment,leading to low strength and high supersaturation of solute atoms.In a subsequent paint-bake treatment,the presence of highly supersaturated solute atoms and high concentrated free vacancies moderated the activation energy barrier ofβ’’phase and thus kinetically accelerated the formation ofβ’’.Consequently,the trace Sn additions enhanced the bake-hardening responses of the pre-aged alloys significantly.The Sn-containing pre-aged Al-Mg-Si alloys with low strength and great bake-hardening responses hold promising potential for automotive body skin applications.展开更多
基金The financial support from National Key Research and Development Plan(No.2016YFB0701202)State Key Laboratory of Powder Metallurgy Central South University,China(No.1991DA105636),are greatly acknowledged.
文摘Phase equilibria of the Mg-Sn-Ag system in Mg-rich corner at 320 and 400℃ were experimentally investigated with nine ternary alloys subjected to electron probe microanalysis and X-ray diffraction techniques.No ternary compounds were observed at both isothermal sections.Two three-phase triangles,i.e.hcp(Mg)+Mg_(2)Sn+Mg_(3)Ag and Mg_(2)Sn+Mg_(3)Ag+MgAg(bcc_B2),were both observed at 320 and 400℃.A new three-phase region of Ag3Sn+Mg2Sn+MgAg(bcc_B2)was additionally observed at 320℃,which implied that the binary phase Ag3Sn has a considerable solubility of Mg in the ternary system at the temperature.And the maximal solubility of Mg in Ag3Sn was measured to be 27.2 at.%.This result is not consistent with the thermodynamic calculated isothermal section at 350℃ from Wang et al.[11]and put forward a new requirement or refinement for the optimization of the Mg-Sn-Ag ternary system.At 400℃,the maximal solubility of Sn in the Mg3Ag phase was determined to be about 3.0 at.%Sn,and the solubility of Ag in Mg2Sn was negligible.The temperature of ternary eutectic reaction at Mg-rich corner(L↔hcp(Mg)+Mg_(54)Ag_(17)+Mg_(2)Sn)was measured by differential scanning calorimetry.The partial isothermal sections in Mg-rich corner of the ternary system at 320 and 400℃ were then constructed based on the above experimental data.
基金supported by the National Basic Research Program of China (No. 2013CB632205)the National Key Research and Development Program of China (No. 2016YFB301105)
文摘Microstructure and mechanical properties of a new high-strength Mg–6 Zn–4 Al–1 Sn alloy were investigated. Microstructure of the as-cast Mg alloy exhibited partially divorced characteristics. The dendritic structure of the Mg–6 Zn–4 Al alloy was significantly refined with the addition of 1%（in weight） Sn, but Mg2 Sn phases were not formed. In addition, an icosahedral quasi-crystal phase was formed in the as-cast Mg–6 Zn–4 Al–1 Sn alloy. It was found that after the double-aging treatment through two different heat treatments on the Mg–6 Zn–4 Al–1 Sn alloy, the precipitates were finer and far more densely dispersed in the matrix compared with single-aged counterpart, resulting in a significant improvement in tensile strength with yield strength, ultimate tensile strength and elongation of 175 MPa, 335 MPa and 11%,respectively.
基金financially supported by the National Key R&D Program of China(No.2018YFB2001800).
文摘Effects of additions of trace Sn on the bake-hardening responses of a pre-aged Al-0.85 Mg-0.85 Si(in wt%)alloy were investigated through mechanical tests,differential scanning calorimetry,electrical resistivity and transmission electron microscopy.Results indicate that trace Sn additions reduced the number density of pre-aging clusters by inhibiting the formation of unstable counterpart during pre-aging treatment,leading to low strength and high supersaturation of solute atoms.In a subsequent paint-bake treatment,the presence of highly supersaturated solute atoms and high concentrated free vacancies moderated the activation energy barrier ofβ’’phase and thus kinetically accelerated the formation ofβ’’.Consequently,the trace Sn additions enhanced the bake-hardening responses of the pre-aged alloys significantly.The Sn-containing pre-aged Al-Mg-Si alloys with low strength and great bake-hardening responses hold promising potential for automotive body skin applications.
