Effect of heat treatment environment on mechanical properties and microstructure of alumina fibers

Abstract

Continuous alumina fiber-reinforced ceramic matrix composites are one of the ideal thermal structural materials for aerospace applications. Mechanical properties of composites in different environments depend on the mechanical properties of continuous alumina fibers, but effect of different heat treatment environments on mechanical properties and microstructure of alumina fibers has rarely been reported. In this study, mechanical properties and microstructure of Nextel 610 fibers from different heat treatment atmosphere, heat treatment temperature and heat treatment time were characterized in detail. It is found that when heat treatment temperature is increased from 1000 ℃ to 1400 ℃, tensile strength of N610 fibers is decreased from 2.58 GPa to 0.94 GPa and surface grain size increased from 97.3 nm to 184.1 nm in air; tensile strength of N610 fibers is decreased from 2.18 GPa to 0.95 GPa and surface grain size is increased from 91.3 nm to 171.7 nm in steam. Many internal defects in N610 fibers because of H2O molecules diffuse into fibers at high temperature. At the same process of heat treatment, tensile strength and growth rate of surface grains of N610 fibers in steam are lower than those in air.

Keywords

• heat treatment environment
• steam
• alumina fiber
• mechanical property
• microstructure