Mechanical behavior of high-density nanocrystalline gold prepared by gas deposition method

Nanocrystalline gold (n-Au) specimens with the theoretical density were prepared using the gas deposition method, and mechanical tests were carried out. In the elastic range, the Young's modulus found below 80 K for n-Au specimens with mean grain size of 26-60 nm is higher than 92% of the bulk value, suggesting that the Young's modulus in the grain boundary region is higher than 70% of the bulk value. Above 200 K, anelastic strain due to a certain relaxation in the grain boundary region increases with increasing temperature, giving a decrease in the Young's modulus. Plasticity tests were made near room temperature for n-Au specimens with mean grain size of 15-60 nm. The Hall-Petch relationship is observed in the Vickers microhardness tests with a hording time of 10 s, and creep deformation proceeds in quasi-static tensile tests for 10(3)-10(5) s, indicating that the preferable plastic deformation process near room temperature in n-Au is governed by not only the stress level but also the strain rate. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.