It is well known that the heat treatment is able to initiate various phenomena in materials, e.g. change in their structure, emergence of mechanical stresses, occurrence chemical reactions, etc. In this work we investigate the influence of temperature on the structure evolution of copper pentagonal micro- and nanoobjects such as icosahedral small particles and pentagonal prismatic rod-like crystals produced by electrodeposition of metals. Heating the crystals and the microparticles was performed either in vacuum, or on air, or in a variety of environments. Changes in structure and morphology were investigated by electron microscopy and ion-beam cutting. Changes in phase composition were detected by X-ray diffraction. It was established that heating copper pentagonal objects on air to the temperatures above 250°C whiskers of the copper oxide CuO are formed on the surface of the objects. The maximum concentration of whiskers per surface area is found after annealing at 400°C. Annealing at higher temperatures (over 500°C) results in the formation of the porous materials structure, which is most clearly visible after annealing at 600°C. Applying the method of the ion-beam cutting it was also found that the prolonged annealing of copper particles leads to the formation large internal cavities.
This study has been performed under the support from the grant № 14.B25.31.0011 of the Ministry of Education and Science of Russian Federation (resolution # 220) at Togliatti State University.