微觀組織演變
( 東南大學(xué) 材料科學(xué)與工程系， 南京 210096)
摘 要: 研究了粉末冶金法制備泡沫鋁時泡沫孔結(jié)構(gòu)及胞壁微觀組織變化的規(guī)律。泡沫鋁發(fā)泡時經(jīng)歷微膨脹、 顯著膨脹和收縮等過程； 孔結(jié)構(gòu)經(jīng)歷了形核和長大， 以及在毛細(xì)力和重力驅(qū)動下泡壁熔體的流動引起的合并粗化和孔隙率自上而下梯度減小等演化過程。加熱時， 鋁/硅顆粒邊界處硅的擴(kuò)散層首先熔化，并沿著鋁顆粒邊界擴(kuò)散， 最終使鋁硅粉末復(fù)合體完全熔化而實現(xiàn)合金化。 實驗發(fā)現(xiàn)泡壁的凝固組織與典型的變質(zhì)處理后的鑄造鋁硅合金的組織類似。
關(guān)鍵字: 泡沫鋁; 粉末冶金; 孔結(jié)構(gòu); 微觀組織
aluminum foam during powder metallurgical foaming
LIANG Xiao-jun, HE De-ping
（ Department of Materials Science and Engineering,
Southeast University, Nanjing 210096, China）
Abstract: Evolution of pore morphology and cell wall microstructure of aluminum foam during powder metallurgical foaming was studied. It was found that aluminum foam shows three stages during foaming, that is tiny expansion, remarkable expansion and shrinkage; and the pore morphology goes through three stages, that is nucleation and growth, merging and coarsening, and the porosity decreasing from the upper part of the foam to the lower part of the foam. The merging and porosity gradient of the pore structures were resulted from capillarity-driven and gravity-driven melt flow within the melt foam column. The silicon diffusing layer along the boundary of aluminum and silicon powders melts firstly during the heating, and then the melt diffuses along the boundary of the aluminum powders, resulting in the entire alloying between aluminum and silicon powders. The experiment shows that the solidified cell wall microstructures are similar to those of typical modified cast Al-Si alloys.
Key words: aluminum foam; powder metallurgy; pore morphology; microstructure
