(SiC_w+B_4C_p)/MB15 Mg基复合材料的微观结构

MICROSTRUCTURE STUDIES OF A (SiC_W+B_4C_p)/MB15 MAGNESIUM ALLOY MATRIX COMPOSITE

利用高分辨电镜研究了（ＳＩＣ_ｗ＋Ｂ_４Ｃ_ｐ）／ＭＢ１５ Ｍｇ合金基复合材料的微观结构、ＳｉＣ晶须的表面附着呈截角八面体形状的 ＭｇＯ纳米颗粒．此外， ＭｇＢ_２和 ＭｇＯ共生在 ＳｉＣ晶须的表面，三者之间存在固定的晶体学取向关系：［１１０］ＳｉＣ ／／［１１０］ＭｇＯ／／［１１２０］ＭｇＢ_２和（１１１）ＳｉＣ／／（１１１）ＭｇＯ／／（０００１）ＭｇＢ_２ ＭｇＢ_２相呈六角盘状几何外形，在 Ｍｇ合金中其界面能的各向异性显著．此外，还发现了 ＳｉＣ和 Ｍｇ存在的一种晶体学取向关系： ［１１１］ＳｉＣ／／ ［０００１］Ｍｇ和（２０２）ＳｉＣ ／／（１１２０）Ｍｇ．研究结果表明，在 Ｍｇ合金复合材料中， ＳｉＣ比

The microstructure of a (SiC_W + B_4C_p)/MB15 magnesium alloy matrix composite was studied by high--resolution electron microscopy (HREM). MgO nanocrystalline particle with cubooctahedral in shape was found at SiC/Mg interface. Besides, MgO co-existing with MgB_2 was also observed at SiC/Mg interface. There exists a consistent orientation relationship (O.R.) among SiC, MgO and MgB_2, i.e. [110]sic // [110]MgO// [1120]MgB_2 and (111)SiC // (111)MgO // (0001)MgB_2 MgB_2 is hexagonal plate-like in shape. There is a large energy anisotropy of the interfaces between MgB_2 and Mg. An O.R. between SiC and Mg was found, i.e. [111]SiC // [0001]Mg and (202)SiC // (1120)Mg. Experimental results indicate that SiC is more stable than B_4C in the (SiC_W+B_4C_p)/ MB15 magnesium alloy matrix composite.