Kum, D Kim, WJ 2024-01-21T17:41:53Z 2024-01-21T17:41:53Z 2021-09-03 1998-01 0255-5476 https://pubs.kist.re.kr/handle/201004/143435 Many dispersion strengthened aluminum alloys and discontinuously reinforced composites exhibit high strain rate superplasticity when they are processed into ultra-fine grain sizes by powder metallurgy using rapidly solidified or mechanically alloyed powders. Grain boundary sliding is considered to be the mechanism for the superplasticity by incorporating the concept of threshold stress. The threshold stress introduced to fit the stress vs. strain-rate data decreases the apparent now stress, and is strongly temperature dependent. The temperature dependence of threshold stress appeared in literatures has been reviewed, and analyzed by a thermally activated process. The modulus-compensated threshold stress data fit well with an Arrhenius-type plot, and two modes of thermally activated processes an be visualized. At lower temperatures, the activation energy for the threshold stress is about 50kJ/mole or less, which is similar to the that interpreting the creep of similarly processes aluminum alloys. At higher temperatures near an incipient melting condition, the activation energy is much higher, and it's origin cannot be explained by various models used in the literature, Based on the serrated now curves and microstructural observation in the Al-10wt%Ti alloy, the solute drag against gliding dislocations has been suggested as a possible source for the threshold stress at very high temperatures. English TRANSTEC PUBLICATIONS LTD MATRIX COMPOSITES DEFORMATION MECHANISMS BEHAVIOR CREEP Threshold stress in high strain rate superplasticity of powder metallurgy aluminum alloys and composites Article 10.4028/www.scientific.net/MSF.304-306.241 1 TOWARDS INNOVATION IN SUPERPLASTICITY II, v.304-3, pp.241 - 247 TOWARDS INNOVATION IN SUPERPLASTICITY II 304-3 241 247 scie scopus 000082112300035 2-s2.0-33751364231 Materials Science, Ceramics Materials Science, Multidisciplinary Materials Science, Composites Materials Science Article; Proceedings Paper MATRIX COMPOSITES DEFORMATION MECHANISMS BEHAVIOR CREEP high strain rate superplasticity threshold stress Al-Ti alloys Al-matrix composites DS aluminum alloys