Tailoring microstructure of Mg-Zn-Y alloys with quasicrystal and related phases for high mechanical strength.
Tailoring microstructure of Mg-Zn-Y alloys with quasicrystal and related phases for high mechanical strength.
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DOI：
10.1088/1468-6996/15/4/044803
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发表时间：
2014-08
影响因子：
5.5
通讯作者：
Singh A
中科院分区：
文献类型：
--
作者：
Singh A
在Mg-Zn-RE（RE = Y，Gd，Tb，Dy，Ho或Er）合金的平衡相图上出现了一个稳定的二十面体（i-）相，即具有二十面体（五重）对称性的准晶相，这为开发一系列新的结构用镁合金开辟了一个有趣的可能性。基于i相的合金已经研究了14年。超高强度与良好的延展性相结合。在这里，我们展示了两种策略，用于定制非常高强度的Mg-Zn-Y合金的微观结构。其中之一涉及通过棒状沉淀物的精细分布来强化，其中基质晶粒尺寸不是关键的。该合金在480 °C的高温下固溶以溶解大部分i相，然后进行高温挤压（约430 °C）和低温时效以再沉淀具有精细尺寸分布的相。首先，在这个过程中所涉及的相变进行了描述。析出物的结构与i相的接近性被带出。通过该工艺，在晶粒尺寸为20 μm时，获得了超过370 MPa的拉伸屈服强度。在另一种策略中，将合金冷铸，然后在约250 °C的低温下挤出。由于i相的存在，通过增强的再结晶产生超细晶粒。同时，纳米尺寸的沉淀物在从过饱和基体挤出期间动态地沉淀。可获得高达400 MPa的超高拉伸强度和12 - 16%的延展性。显微组织分析表明，强化的i相发生在挤压过程中的增强再结晶。它产生超细晶粒尺寸以提供非常高的强度，以及适度的纹理以获得良好的延展性。细小的i相和析出相的分布有助于强化和提供组织稳定性。因此，通过利用不同的强化效应，在非常宽的晶粒尺寸范围内展示了超高强度。
The occurrence of a stable icosahedral (i-) phase, which is quasicrystalline with an icosahedral (fivefold) symmetry, on the equilibrium phase diagram of Mg–Zn–RE (RE = Y, Gd, Tb, Dy, Ho or Er) alloys opened up an interesting possibility of developing a new series of magnesium alloys for structural applications. Alloys based on the i-phase have been studied for the past 14 years. Ultra-high strengths combined with good ductility have been shown. Here we show two strategies for tailoring microstructures for very high strengths in Mg–Zn–Y alloys. One of them involves strengthening by a fine distribution of rod-like precipitates, where the matrix grain size is not critical. The alloy is solutionized at a high temperature of 480 °C to dissolve a large part of the i-phase, followed by a high temperature extrusion (∼430 °C) and a low temperature ageing to reprecipitate phases with fine size distribution. At first, phase transformations involved in this procedure are described. The closeness of the structure of the precipitates to the i-phase is brought out. By this procedure, tensile yield strengths of over 370 MPa are obtained in grain sizes of 20 μm. In another strategy, the alloys are chill cast and then extruded at low temperatures of about 250 °C. Ultra-fine grains are produced by enhanced recrystallization due to presence of the i-phase. At the same time nano-sized precipitates are precipitated dynamically during extrusion from the supersaturated matrix. Ultra-high tensile strengths of up to 400 MPa are obtained in combination with ductility of 12 to 16%. Analysis of the microstructure shows that strengthening by the i-phase occurs by enhanced recrystallization during extrusion. It produces ultra-fine grain sizes to give very high strengths, and moderate texture for good ductility. Fine distribution of the i-phase and precipitates contribute to strengthening and provide microstructre stability. Ultra-high strength over a very wide range of grain sizes is thus demonstrated, by utilizing different strengthening effects.
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DOI：
10.1016/0956-716x(93)90584-f
发表时间：
1993-06-15
期刊：
SCRIPTA METALLURGICA ET MATERIALIA
影响因子：
--
作者：
LUO, ZP;ZHANG, SQ;ZHAO, DS
通讯作者：
ZHAO, DS
DOI：
10.1016/j.msea.2012.01.087
发表时间：
2012-03-30
影响因子：
6.4
作者：
Rosalie, Julian M.;Somekawa, Hidetoshi;Mukai, Toshiji
通讯作者：
Mukai, Toshiji
DOI：
10.1016/j.msea.2005.02.036
发表时间：
2005-04-25
影响因子：
6.4
作者：
Singh, A;Watanabe, M;Tsai, AP
通讯作者：
Tsai, AP
影响因子：
3.7
作者：
ELSER, V
通讯作者：
ELSER, V
影响因子：
9.4
作者：
Bae, DH;Kim, SH;Kim, WT
通讯作者：
Kim, WT