The thermal stability of high-energy ball-milled nanostructured Cu

• Published in: Materials in engineering Vol. 50; pp. 22 - 26
• Main Authors: Tao, J.M., Zhu, X.K., Scattergood, R.O., Koch, C.C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2013
• Subjects: High-energy ball milling; Nanostructured copper; Strain release; Thermal stability; Nanostructured copper; Strain release; High-energy ball milling; Thermal stability
• ISSN: 0261-3069
• DOI: 10.1016/j.matdes.2013.02.083

•High-energy ball-milled nanostructured (NS) Cu shows a high thermal stability.•High Hv of 1.7GPa of NS Cu does not decrease after annealing at 500°C for 1h.•Cu annealed below 500°C has small activation volume and high strain rate sensitivity.•Strain release process occurs prior to grain growth process during isothermal treatment. The thermal stability of nanostructured (NS) Cu prepared by high-energy ball milling was investigated. The as-prepared samples were isothermal annealed for 1h in the temperature range of 200–1000°C. Effects of annealing on NS Cu samples were studied by means of Vickers hardness test, differential scanning calorimetry (DSC) and stress relaxation test. The exceptional high microhardness of as-prepared Cu sample of 1.7GPa was not detected to decrease after annealing at 500°C for 1h with corresponding small value of activation volumes V* of 22.6b3 and high value of strain rate sensitivity m of 0.0176. A prominent decrease of microhardness was detected after higher temperature annealing with a rapidly increase of activation volume and decrease of strain rate sensitivity. The present investigation demonstrates that the thermal stability of NS Cu prepared by high-energy ball milling is determined by not only the grain size but also the microstructure of grain boundaries, and during annealing process, the strain release process occurred prior to the grain growth process, therefore, the NS Cu has a relatively high thermal stability.