Hydrogenation of amorphous and nanocrystalline Mg-based alloys
Hydrogenation of amorphous and nanocrystalline Mg-based alloys
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DOI：
10.1016/s0925-8388(99)00035-3
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发表时间：
1999-06-01
影响因子：
6.2
通讯作者：
Köster, U
中科院分区：
文献类型：
--
作者：
Spassov, T;Köster, U
采用快淬法(熔体旋压)制备了非晶态和纳米晶镁基合金，并对其氢化性能进行了研究。还研究了淬火和氢化合金的热稳定性和晶化行为。结果表明，铸态纳米晶/非晶态Mg(75)Ni(20)Mm(5)(Mm=Ce，富La混合稀土)合金具有最佳的氢化动力学和吸氢性能，最大吸氢量为4.0wt.%H。淬态纳米晶和完全晶化(晶粒度在100~150 nm)的Mg(75)Ni(20)Mm(5)合金的氢化性能差异不大。与所研究的其他镁基合金相比，非晶态和晶化(热处理后)的镁合金表现出较慢的氢化动力学和较低的吸氢容量。由于氢在非晶相中的扩散速度较快，非晶态合金比部分晶化和完全晶化的合金具有更快的初始氢化动力学，但不同微观组织的合金的吸氢能力基本相同。α-Mg(对于Mg87Ni12Y1)的初晶化发生在160C左右，随后残留的非晶基质转变为亚稳相，命名为FeE-Mg_6Ni(与FeE_6Pd同构(α(O)=2.0108 nm))。这种中间亚稳定相在进一步的退火过程中(约300℃)分解成平衡相镁镍和镁。铸态Mg(75)Ni(20)Mm(5)合金的第一次晶化反应产物为Mg2Ni，很可能是通过淬火后的Mg2Ni纳米晶的生长实现的。第二个反应对应于残留的非晶基质转变为Mg(17)mm(2)。(C)1999 Elsevier Science S.A.保留所有权利。
Amorphous and nanocrystalline Mg-based alloys were produced by rapid quenching (melt-spinning) and their hydrogenation properties were studied. The thermal stability and crystallization behaviour of the as-quenched and hydrogenated alloys were investigated as well. It was found that the as-cast nanocrystalline/amorphous Mg(75)Ni(20)Mm(5) (Mm=Ce, La-rich mischmetal) alloy possesses the best hydriding properties (hydrogenation kinetics and hydrogen absorption capacity) with maximum hydrogen capacity of 4.0 wt.% H. The difference in the hydriding properties of the as-quenched nanocryrstalline and completely crystallized (with grain size in the range of 100-150 nm) Mg(75)Ni(20)Mm(5) alloys was found to be insignificant. The amorphous and crystallized (after heat treatment) Mg87Ni12Y1 alloys show slower hydriding kinetics and lower hydrogen absorption capacity compared to the other Mg-based alloys studied. The amorphous Mg87Ni12Y1 exhibits faster initial hydrogenation kinetics than the partially and fully crystallized alloys with the same composition, due to faster hydrogen diffusion in the amorphous phase, but the hydrogen absorption capacity of all Mg87Ni12Y1 alloys having different microstructure is practically the same.The crystallization of melt-spun Mg(75)Ni(20)Mm(5) and Mg87Ni12Y1 alloys is a two-step process. The primary crystallization of alpha-Mg (for Mg87Ni12Y1) takes place at about 160 degrees C, followed by transformation of the residual amorphous matrix into a metastable phase, assigned as fee Mg6Ni (isomorphic with fee Mg6Pd (alpha(o)=2.0108 nm)). This intermediate metastable phase decomposes during further annealing (at about 300 degrees C) into the equilibrium phases Mg2Ni and Mg. The product of the first crystallization reaction for the as-cast Mg(75)Ni(20)Mm(5) alloy is Mg2Ni, most probably realized by growth of the quenched-in Mg2Ni nanocrystals. The second reaction corresponds to transformation of the residual amorphous matrix into Mg(17)Mm(2). (C) 1999 Elsevier Science S.A. All rights reserved.