Al_2O_3-ZrO_2-Spinel三元纳米复相陶瓷超塑性变形及组织演变

采用真空热压烧结工艺制备了三元纳米复相陶瓷并进行了超塑性压缩试验.结果表明:纳米复相陶瓷中的第二相在烧结和变形过程中有效地阻止了基体Al_2O_3的晶粒长大.在1650 ℃材料表现出良好的高应变速率超塑变形能力,变形抗力小于30 MPa.微观组织观察表明由于变形过程中存在有益压应力,材料变形后晶界处未出现空洞,经变形量为60%的压缩变形后材料中存在较高密度的位错,位错主要存在于尖晶石和氧化锆第二相中,基体Al_2O_3的晶粒仍为等轴状,表明位错运动对晶界滑移起到了积极地协调作用.

Superplastic Deformation and Microstructure Evolution of Ternary Nanocomposite Ceramic Al_2O_3-ZrO_2-Spinel

A ternary nanocomposite ceramic was prepared by hot-pressing sintering in vacuum and deformed by the superplastic compressive test. The results demonstrate that as-sintered material behaves high strain rate superplasticity at 1650 ℃. During compression the maximum deformation pressure was below 30 MPa, because the dispersed second phases inhibited the growth of the matrix alumina grains in deformation as well as in sintering. The study on the deformed microstructure indicated that due to the existence of beneficial compressive stress state, there was no cavitation at the grain boundaries in the deformed material experienced 60% deformation, while the dislocation density increased obviously in the deformed material. The dislocations mainly existed in both zirconia and spinel grains after deformation and the alumina matrix grains kept equiaxed. It can be deduced that during superplastic deformation the grain boundary sliding was well accommodated by the dislocation movement in some extent.