Solute segregation and precipitation in a creep-resistant Mg-Gd-Zn alloy
Solute segregation and precipitation in a creep-resistant Mg-Gd-Zn alloy
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DOI：
10.1016/j.actamat.2008.08.025
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发表时间：
2008-12-01
期刊：
影响因子：
9.4
通讯作者：
Hono, K.
中科院分区：
文献类型：
--
作者：
Nie, J. F.;Oh-ishi, K.;Hono, K.
Mg-1Gd-0.4Zn-0.2Zr（at.%）抗蠕变合金中的溶质偏析和析出相用三维原子探针和高角环形暗场扫描透射电子显微镜研究了250和200 ℃等温时效的合金。在淬火状态下检测到Gd和Zn原子的共偏聚，这有助于在这种条件下硬度的大幅度增加。等温时效期间的沉淀涉及亚稳相γ "和γ“的形成，其中γ"是关键的强化相。在250摄氏度下老化1000小时后，未检测到平衡相γ。γ相具有有序的六方结构（棒2 m上的空间群P（6），a = 0.560nm，c = 0.444nm）和大约Mg（70）Gd（15）Zn（15）的原子组成，并且形成为具有单个晶胞高度的厚度的（0001）（α）板。γ '相具有无序的六方结构（空间群P（3），m ~ 1，a = 0.321nm，c = 0.781nm），原子组成约为MgGdZn。γ '相也形成为薄的（0001）（α）。板，但它有一个更大的纵横比。γ '相的形成涉及大的剪切应变，并且它通常形成于孪晶相关的板中以自适应该剪切应变。(C)2008 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Solute segregation and the precipitate phases in a creep-resistant Mg-1Gd-0.4Zn-0.2Zr (at.%) alloy aged isothermally at 250 and 200 degrees C have been examined using it three-dimensional atom probe and high-angle annular dark-field scanning transmission electron microscopy. Co-segregation of Gd and Zn atoms is detected in the as-quenched condition, and this contributes to the large hardness increase in this condition, Precipitation during isothermal ageing involves the formation of metastable phases gamma '' and gamma', with gamma '' as the key strengthening phase. The equilibrium phase gamma is not detected for ageing up to 1000 h at 250 degrees C. The gamma '' phase has an ordered hexagonal Structure (space group P (6) over bar 2m, a = 0.560 nm, c = 0.444 nm) and an atomic composition or approximately Mg(70)Gd(15)Zn(15), and forms as (0001)(alpha) plates with a thickness of a single unit cell height. The gamma' phase has a disordered hexagonal Structure (space group P (3) over bar m1, a = 0.321 nm, c = 0.781 nm) and an atomic composition of about MgGdZn. The gamma' phase also forms as thin (0001)(alpha). plates, but it has a much larger aspect ratio. The formation of the gamma' phase involves a large shear strain, and it often forms in twin-related plates to self accommodate this shear strain. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.