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研究一种镁基Mg-10Ni-2Mm(摩尔分数,%)储氢合金在不同凝固速率下的组织演化。结果表明:增加凝固速率可以大幅度细化合金条带的晶粒;采用的石墨冷却轮表面速度为3.1,10.5和20.9m/s时,可以分别获得微晶、纳米晶和非晶组织;当冷却轮盘表面速度为3.1m/s时,快淬试样完全结晶化,组织中除了少量富Mm晶粒外,形成了粗大的Mg和Mg2Ni微晶;加快冷却轮盘表面速度到10.5m/s时,大量的纳米颗粒形成,组织由大量的Mg和Mg2Ni纳米晶组成;进一步加快速度到20.9m/s时,形成了包括非晶和纳米晶的混合组织。理想的组织是非晶基体上析出大量纳米晶,这样的组织有望获得最大的储氢容量和优异的吸放氢动力学。
The microstructure evolution of a Mg-based Mg-10Ni-2Mm (molar fraction,%) hydrogen storage alloy at different solidification rates was investigated. The results show that the increase of solidification rate can greatly refine the grain of the alloy strip. When the surface velocity of the graphite cooling wheel is 3.1, 10.5 and 20.9 m / s, the crystallites, nanocrystalline and amorphous structures can be obtained respectively. When the cooling wheel surface velocity is 3.1m / s, the quenched specimen is completely crystallized, and the coarse Mg and Mg2Ni crystallites are formed except a small amount of rich Mm grains in the microstructure; the surface speed of the cooling wheel is accelerated to 10.5m / s, a large number of nano-particles formed, the organization consists of a large number of Mg and Mg2Ni nanocrystalline components; to further speed up to 20.9m / s, the formation of a mixed structure including amorphous and nanocrystalline. The ideal organization is a large number of nanocrystals precipitated on an amorphous substrate, such a structure is expected to obtain maximum hydrogen storage capacity and excellent hydrogen absorption and desorption kinetics.