Y2O3添加对MA-CA2-CA6复合材料烧结行为的影响

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。

Effect of Y2O3 Addition on Sintering Behavior of MA-CA2-CA6 Composite

In order to adapt the demands for the lightweight of materials,MA-CA2-CA6composite was prepared at 1 400—1 600 ℃ by addition of Y2O3 micro powder,and the effect of Y2O3 addition on densification behavior of the composite was discussed. The results showed that the added Y2O3 dissolved to CA6,MA phases by substituting Ca2+,Mg2+,which mainly promoted the growth of MA grains in advance,while the abnormal growth of CA6 grains with high aspect ratio were inhibited.Furthermore,the excess Y2O3 reacted with Al2O3 to form the Y3Al5O12 phase,which further inhibited the formation and abnormal growth of CA6 grains with high aspect ratio,and the growth of MA grains in advance occupied the growing space of CA6 grains,thus the micro-structure of CA6 grains was a more equiaxed morphology,instead of anisotropic growth to platelet structure.Based on those factors, the sintering activity of MA-CA2-CA6 composite was synergistically promoted.As a result,MA-CA2-CA6 composite was obtained, with the apparent porosity decreased from 19.2% to 4.8% and the bulk density increased from 2.78 g/cm3to 3.24 g/cm3 after firing at 1 600 ℃ for 2 h by addition of 2% Y2O3,and the crystal phase of MA,CA2,CA6 and a spot of Y3Al5O12 phases was interleaved distributed with textured microstructure in MA-CA2-CA6 composite,which is considered to be favorable to improve the mechanical properties of MA-CA2-CA6 composite.