In Situ Monitoring of the Low Temperature Degradation of Tetragonal Zirconia with Impedance Spectroscopy

✍ Scribed by X. Guo

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 208 KB
• Volume: 2
• Category: Article
• ISSN: 1438-1656
• DOI: 10.1002/1527-2648(200009)2:9<604::aid-adem604>3.0.co;2-y

✦ Synopsis

In Situ Monitoring with Impedance Spectroscopy creases only in the terminal stage of the test, indicating the beginning of the tertiary stage more precisely than the creep curve. Thus, the beginning of the tertiary stage may be characterized by increasing amount of damage processes.

Figure shows the creep rate and the AE response of the AZ91-Saffil MMC in the as-cast condition loaded by 70 MPa at 200 C. This sample shows an enhanced creep resistance in comparison with the other MMCs. To attain fracture, it was necessary to increase the stress to 95 MPa after 4 days of testing. The AE response of this sample may be interpreted in a similar way to that of the sample in the T6 condition.

The creep behavior and related structure changes in various Mg±based metal matrix composites subjected to thermal and/or mechanical loading were investigated by the AE technique. The materials show different resistance to thermal and/or mechanical loading. The creep strain is much lower at thermal loading. However, the AE response shows that thermal loading can produce locally important structure changes (dislocation generation and motion) and plastic deformation at interfaces. Interfacial sliding and creep damage are main AE sources due to mechanical loading.