Instrumented Indentation and Ultrasonic Velocity Techniques for the Evaluation of Creep Cavitation in Silicon Nitride

Published

April 1, 2003

Author(s)

Gerald V. Blessing, Sheldon M. Wiederhorn, W E. Luecke, Douglas T. Smith

Abstract

Instrumented indentation and ultrasonic wave velocity techniques combined with precise density change measurements and transmission electron microscopy (TEM) were used to investigate the changes of elastic moduli in silicon nitride after tensile deformation up to 3%. Linear dependencies on strain were also found fora the degradation of the indentation modulus, longitudinal and transverse ultrasonic wave velocities, Young''s, shear and bulk moduli and Poisson''s ratio. The results obtained by indentation technique and ultrasonic method were essentially identical. TEM observation confirmed that multigrain junction cavities were responsible for the density changes and the elastic moduli degradation. The density changes were linearly proportional to tensile strain with the slope of 0.75. Thus, cavitation is the dominant creep mechanism in silicon nitride studied. Instrumented indentation and ultrasound velocity techniques are suitable for non-destructive monitoring of creep damage accumulation in ceramic components.

Citation

Journal of Materials Science

Volume

38

Pub Type

Journals

Keywords

cavitation, elastic moduli, instrumented indentation, silicon nitride, tensile creep, ultrasonic velocity

Citation

Blessing, G. , Wiederhorn, S. , Luecke, W. and Smith, D. (2003), Instrumented Indentation and Ultrasonic Velocity Techniques for the Evaluation of Creep Cavitation in Silicon Nitride, Journal of Materials Science (Accessed November 8, 2024)