Y_2O_3添加对MA-CA_2-CA_6复合材料烧结行为的影响

Effect of Y_2O_3 Addition on Sintering Behavior of MA-CA_2-CA_6 Composite

为适应材料轻量化的发展需要,在1 400~1 600℃条件下制备了MA-CA_2-CA_6复合材料,并考察了添加Y_2O_3对该复合材料烧结行为的影响。结果表明,添加的Y_2O_3固溶入了CA_6、MA相中,Y^(3+)通过取代Ca^(2+)、Mg^(2+)有效地促进了MA晶粒的提前长大,抑制了CA_6晶粒的异常长大;另一方面,添加过量的Y_2O_3与体系中的Al_2O_3反应生成Y_3Al_5O_(12)新相,使得CA_6相的生成量减少,同时由于MA相提前长大限制了CA_6相的生长空间,进一步促进了CA_6晶粒形貌由片状向等轴状趋势发展。以上因素共同作用,促进了MA-CA_2-CA_6复合材料的烧结行为。当Y_2O_3的添加量为2%时,经1 600℃保温2h烧成后,试样的显气孔率由19.2%下降至4.8%,体积密度由2.78g/cm^3上升至3.24g/cm^3,制得的MA-CA_2-CA_6复合材料中MA、CA_2、CA_6及少量Y_3Al_5O_(12)晶相呈现交织分布,显微结构致密,力学性能得到改善。

In order to adapt the demands for the lightweight of materials,MA-CA 2-CA 6 composite was prepared at 1 400-1 600℃by addition of Y 2O 3 micro powder,and the effect of Y 2O 3 addition on densification behavior of the composite was discussed.The results showed that the added Y 2O 3 dissolved to CA 6,MA phases by substituting Ca 2+,Mg 2+,which mainly promoted the growth of MA grains in advance,while the abnormal growth of CA 6 grains with high aspect ratio were inhibited.Furthermore,the excess Y 2O 3 reacted with Al 2O 3 to form the Y 3Al 5O 12 phase,which further inhibited the formation and abnormal growth of CA 6 grains with high aspect ratio,and the growth of MA grains in advance occupied the growing space of CA 6 grains,thus the microstructure of CA 6 grains was a more equiaxed morphology,instead of anisotropic growth to platelet structure.Based on those factors,the sintering activity of MA-CA 2-CA 6 composite was synergistically promoted.As a result,MA-CA 2-CA 6 composite was obtained,with the apparent porosity decreased from 19.2%to 4.8%and the bulk density increased from 2.78 g/cm 3 to 3.24 g/cm 3 after firing at 1 600℃for 2 h by addition of 2%Y 2O 3,and the crystal phase of MA,CA 2,CA 6 and a spot of Y 3Al 5O 12 phases was interleaved distributed with textured microstructure in MA-CA 2-CA 6 composite,which is considered to be favorable to improve the mechanical properties of MA-CA 2-CA 6 composite.