組織與力學(xué)性能的影響
(太原理工大學(xué) 材料科學(xué)與工程學(xué)院，太原 030024)
摘 要: 采用一種結(jié)合BC、BA路徑特點(diǎn)的改進(jìn)型路徑BC-UD2、在250 ℃對鑄造Al-10.9%Mg2Si原位復(fù)合材料進(jìn)行等通道轉(zhuǎn)角擠壓(ECAP)來細(xì)化組織、改善Mg2Si增強(qiáng)相形態(tài)及分布狀態(tài)，考察其對力學(xué)性能的影響。結(jié)果表明：經(jīng)BC-UD2路徑8道次ECAP擠壓后，復(fù)合材料基體由約100 μm發(fā)達(dá)的樹枝晶組織細(xì)化為約1.5 μm的細(xì)晶粒組織；原先粗大的漢字狀共晶Mg2Si相被細(xì)化為約0.85 μm的多邊形狀顆粒，趨于均勻分布狀態(tài)，較常規(guī)BC路徑中Mg2Si顆粒沿基體晶界聚集分布狀態(tài)有很大改善；經(jīng)BC-UD2路徑擠壓后復(fù)合材料的抗拉強(qiáng)度由鑄態(tài)的166.9 MPa增大到331.8 MPa，伸長率由鑄態(tài)的0.43%增加到23.6%，分別提高了99%和5 400%；同時也比BC路徑擠壓材料的抗拉強(qiáng)度(297.3 MPa)提高了12%，伸長率(15.15%)提高了56%，綜合力學(xué)性能顯著提高。
關(guān)鍵字: Al-Mg2Si原位復(fù)合材料；等通道轉(zhuǎn)角擠壓；晶粒細(xì)化；顆粒分散；力學(xué)性能
mechanical property of Al-Mg2Si in-situ composite
（College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China）
Abstract:A modified equal channel angular pressing (ECAP) route BC-UD2 combining with the characteristics of routes BC and BA was employed to process an as-cast Al-10.9%Mg2Si in-situ composite at 250 ℃ to refine the microstructure and modify the morphology and distribution of Mg2Si reinforcements. The results show that after 8-pass ECAP processing the matrix is significantly refined from its original developed dendrites of about 100 μm in the as-cast state to equiaxed grains of about 1.5 μm, and the eutectic Mg2Si from coarse Chinese script cells to fine discrete polygonal particles of about 0.85 μm which are redistributed more homogeneously than those by the conventional route BC, where the refined Mg2Si particles still congregate seriously along the matrix grain boundary. Accordingly, the ultimate tensile strength and the elongation of the composite processed by route BC-UD2 are enhanced from 166.9 MPa and 0.43% in the as-cast state to 331.8 MPa and 23.46%, increased by 99% and 5 400%, respectively, and further increased by 12% and 56% when compared to those by route BC, and thus the comprehensive mechanical properties are enhanced remarkably.
Key words: Al-Mg2Si in-situ composites; equal channel angular pressing/extrusion; grain refinement; particle redistribution; mechanical property
