Influence of the heat treatment on the structural parameters of the CuCrZr-TiB2 alloy

Abstract

Powder metallurgy (PM) is used for the CuCrZr-TiB2 alloy synthesis by employing mechanical alloying and hot pressing techniques. Powder mixture containing prealloyed CuCrZr powder, 7 wt.% Ti, and 3.2 wt.% B was firstly homogenized, and then mechanically alloyed (MA) for 27 hours. MA powders were hot pressed (HP) in protective atmosphere at temperature of 950 ℃, with applied pressure of 45 MPa, and duration of 2.5 hours. Heat treatment (HT) of HP CuCrZr-TiB2 alloy was performed in two steps: (1) solution annealing (SA) at 1000 ℃ for 5 hours, and (2) age hardening (AH) at 470 ℃ for 3 hours. Changes in the structural parameters of the MA powders, and obtained compacts (HP, HT) were investigated by X- ray diffraction. Williamson-Hall equation was applied for calculation of the crystallite sizes (D, nm), lattice parameter (nm), and lattice strain (ε, %). The results show that heat treatment has significant influence on the structural parameters. After each step of HT, crystallite size and lattice strain decrease compared to HP samples owing to more homogeneous distribution of TiB2, precipitate formation, and consequently restriction of the large grains recrystallization. Heat treatment, as well as structural parameters exhibit great influence on the mechanical properties of CuCrZr alloy. Therefore, these results indicate relation between specific heat treatment parameters, and structural parameters of the CuCrZr alloy, which may contribute to the future design of CuCrZr alloy with improved mechanical and physical properties