Significance of homologous temperature in softening behavior and grain size of pure metals processed by high-pressure torsion

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:528

Article

Edalati, Kaveh¹  Horita, Zenji¹ 

[1] Kyushu Univ, Fac Engn, Dept Mat Sci & Engn, Fukuoka 812, Japan

关键词: Hardness;    Grain size;    High-pressure torsion;    Ultrafine-grained materials;    Severe plastic deformation;   

DOI  :  10.1016/j.msea.2011.06.080

来源: Elsevier

【 摘 要 】

High purity metals with low melting temperatures such as indium (99.999%), tin (99.9%), lead (99%), zinc (99.99%) and aluminum (99.99%) were processed using high-pressure torsion (HPT). An unusual softening behavior was observed in all these metals after processing by HPT at room temperature. Pure copper (99.99%) and palladium (99.95%) were used to simulate the softening behavior due to a thermal effect by processing and subsequently holding at the temperatures equivalent to room temperature of pure Al. It is shown that a hardness peak appears in any metal by static softening after processing by HPT at a homologous temperature of 0.32 which is equivalent to room temperature of pure Al. The contribution of dynamic softening on hardness decrease becomes more important as the homologous temperature and stacking fault energy increase. Microstructural examinations indicate that, although the stacking fault energy influences the rate of the microstructural evolution, the homologous temperature appears to be a dominant parameter to determine the steady-state grain size after processing by HFT. (C) 2011 Elsevier B.V. All rights reserved.

【 授权许可】

Free