Abstract
There is keen interest in using Ti alloys as lightweight structural materials for aerospace and automo-tive industries.However,a long-standing problem for these materials is their poor oxidation resistance.Herein,we designed and fabricated a Ti5Si3 reinforced Ti-4(wt.％)Mo composite with two-scale network architecture by low energy milling and spark plasma sintering.It displays superior oxidation resistance at 800℃owing to the in-situ formation of a multi-component surface layer.This oxide layer has a dense grain size gradient structure that consists of an outer TiO2 layer and an inner SiO2-padding-TiO2 layer,which has remarkable oxidation resistance and thermal stability.Furthermore,it was revealed that the hitherto unknown interaction between Ti5Si3 reinforcement and nitrogen during oxidation would con-tribute to the formation of a TiN nano-twin interface layer,which accommodates the thermal mismatch strain between the oxide layer and matrix.This,along with high adhesion,confers excellent thermal cy-cling life with no cracking or spallation during long-term oxidation.In this regard,the secure operating temperature of this new composite can be increased to 800℃,which provides a design pathway for a new family of Ti matrix composites for high-temperature applications.
基金项目
国家自然科学基金(51534009)
国家重点研发计划(2017YFB0306001)
Natural Science Foundation of Hunan Province China(2021JJ40750)
Advanced Research Center of Central South University and Shiyan-jia Lab(www.shiyanjia.com)for performing the TEM examination()
万方数据