摘要
以Al Si11合金为对象,选取了预合金化的粉末和元素混合粉末作为前驱体的原料,以Ti H2粉末为发泡剂,采用粉末冷等静压、真空热除气、热挤压成形等工艺制备前驱体、再次加热发泡成型的方法制备了不同时间状态的一系列泡沫铝试样;对系列试样的孔隙率、孔径及其分布、孔形貌等参数的演变规律进行了对比研究;对孔壁微观组织进行了金相表征。结果表明,预合金粉前驱体制备的泡沫铝试样的最大孔隙率为72%,平均孔径为0.59~3.38 mm,孔径分布不均匀;气孔演化过程经历了气孔形核、气孔长大和快速合并阶段,发泡后期出现严重排液现象。元素混合粉前驱体制备的泡沫铝试样的最大孔隙率为84%,平均孔径为0.58~1.99 mm,孔径分布较为均匀;气孔经历了形核、快速合并长大和气孔缓速合并3个阶段。二者相比,元素混合粉前驱体的可发泡性更好、气孔稳定性更好;结合组织分析可知,前驱体中AlSi组织特征(尤其是界面形态)的差异从本质上决定了合金的熔化和凝固行为,进而对气孔形核和演化产生了较大的影响。
By using pre-alloyed powders and mixed elementary powders with composition ratio of Al Si11 as raw material and Ti H2（ titanium hydride） as blowing agent,series of aluminum foam samples were successfully fabricated with methods of cold isostatic pressing,hot vacuum deaeration,hot extrusion and heating foaming molding. The evolution of porosity,pore size and its distribution,pore morphology parameters were studied,and the metallographic of microstructure of hole wall was characterized. The results showed that the maximum porosity was 72%,the average pore diameter distributed from 0. 59 to 3. 38 mm,and pore size distribution was not uniform.For the aluminum foam sample prepared by pre-alloyed powders precursor,the evolution process of precursor went through three stages：pores nucleation,pores growth and pores rapid consolidation,and serious drainage phenomenon happened at late stage. For the aluminum foam sample prepared by mixed elementary powders precursor,the maximum porosity was 84%,the average pore diameter distributed from 0. 58 to 1. 99 mm,pore size distribution was relatively uniform and the evolution process went through pores nucleation,pores rapid growth with consolidation and slow consolidation of pores. Compared with pre-alloyed powders,aluminum foam prepared by mixed elementary powder had higher porosity,smaller pores diameter,more uniform pores and more stable porosity. Combined with microstructure analysis,it could be concluded that the alloy melting and solidification behavior was essentially decided by organization characteristics of Al-Si precursor（ especially the interface morphology）,and thus nucleation and evolution of bubble were affected.
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2017年第9期1003-1011,共9页
Chinese Journal of Rare Metals
基金
国家重点基础研究发展计划项目(2012CB619606)
北京市科技新星计划项目(Z171100001117067)资助
关键词
粉末冶金
泡沫铝
孔结构
powder metallurgy
aluminum foam
pore structure
