球磨Mg_(17)Al_(12)纳米晶/非晶合金的微结构和储氢性能

Microstructures and Hydrogen Storage Characteristics of Nanocrystal/Amorphous Mg_(17)Al_(12) Alloy Prepared by Ball-Milling

采用镁粉和铝粉为原料,通过高能球磨方法制备了Mg17Al12纳米晶/非晶储氢合金,系统研究了球磨时间对合金微结构和储氢性能的影响.结果表明:球磨时间对Mg17Al12合金的微结构和储氢性能有显著影响,随着球磨时间t从10 h延长到100 h,合金发生从晶态(t≤50 h)到纳米晶态(t=70 h)再到非晶态(t=100 h)的结构转变;样品的平均颗粒尺寸随着球磨时间的增加先减小后增大;球磨时间为30、70和100 h后的Mg17Al12合金在350℃时的最大储氢量(氢的质量分数)分别为4.03%、4.27%和4.18%,而相同条件下铸态Mg17Al12合金的最大储氢量只有2.85%;球磨时间为70 h的Mg17Al12纳米晶合金在200、280和320℃的储氢量分别为1.07%、3.02%和4.07%;球磨时间为100 h的Mg17Al12非晶合金在200℃时30 min内的吸氢量(氢的质量分数)可达到2.84%,分别为相同条件下纳米晶合金和铸态合金的2.7倍和5.1倍.

The nanocrystal/amorphous Mg17 Al12 hydrogen storage alloy was prepared by ballmilling with Mg and Al powders as raw materials. The influence of milling time on the microstructure and hydrogen storage characteristic of the alloy was investigated. The results show that the phase structure and hydrogen storage characteristic of the Mg17Al12 alloy are affected greatly by the milling time. As the milling time （t） increases the average particle size of the sample decreases first and then increases, the alloy phase structure evolves from crystalline （t≤50 h） to nanocrystal （t=70 h）, and then to amorphous （t=lO0 h）. The maximum hydrogen storage capacities of the Mg17Al12 alloy ball-milled for 30 h, 70 h and 100 h are 4.03%, 4.27% and 4. 18% at 350 ℃, respectively. The hydrogen storage capacities of the nanocrystal Mg17Al12 （t=70 h） alloy are 1.07% at 200 ℃, 3.02℃ at 280 ℃, and 4. 07% at 320 ℃, respectively. The hydrogen capacities of the Mg17Al12 amorphous alloy （t=100 h） is 2. 84% absorbed in 30 rain at 200 ℃, which is 2. 7 times that of nanocrystal alloy and 5. 1 times that of as-cast alloy.