This paper presents a modified small-angle X-ray scattering (SAXS) method for analyzing the size and shape of hardening particles in steels. Unlike the conventional SAXS approach, which typically analyzes alloy particles of only one morphology, the modified method enables simultaneous evaluation of various types of particles differing in both size and morphology. The essence of the modification to SAXS method is that it takes into account the contribution of the intensity of the separate types of particles with different morphologies to the total true intensity. For each type of particles, shape and structural coefficients are set taking into account their spatial distribution in the analyzed area. To detect the presence of particles of different morphologies in alloys, the experimental patterns are analyzed. First, based on the I(q−n) dependence, the morphology of the existing types of particles was traditionally identified (cylinder / needle (n =1), plate / disk (n = 2), and ellipsoid / sphere (n = 3, 4)). Subsequently, individual regions of the SAXS curve were analyzed in the context of optimizing the size and shape of various particles. The modified SAXS method was tested for analyzing the morphology and size of cementite particles in ferrite-pearlite steel subjected to annealing. As a result, it was shown that during the annealing process of steel, cementite particle morphology in pearlite grains undergoes a stepwise transformation according to the following scheme: lamellar → ellipsoidal → spherical. For the first time, quantitative characteristics of the change in particle size distribution were obtained for different morphologies. The transformation of cementite particle morphology was found to be accompanied by growth, which leads to a decrease in the contribution of dispersion hardening.
Enhancing the strength, hardness, and wear resistance of aluminum alloys can be done through composite forming. According to the methods of production, composites can be classified into two types: ex situ and in situ composites. In ex situ composites, the reinforcing particles do not interact with the matrix, whereas in in situ composites, a chemical reaction occurs between the reinforcing particles and the matrix. Friction stir processing (FSP) is a promising approach to forming in situ composites, as it involves the frictional mixing of solid-state metal through the combined rotational and linear movement of the tool. The aim of this work was to study the impact of multi-pass FSP on the microstructure and microhardness of the in situ composite formed on the surface of an AA6063 alloy with pre-incorporated NiO particles. For this purpose, 4-, 10-, and 20‑pass FSP of AA6063 alloy sheets with grooves filled with fine NiO powder were performed. The chemical reaction between NiO and the aluminum matrix leading to the formation of Al3Ni and Al2O3 was studied using EDS, EBSD and X-ray diffraction techniques. It was found that the quantity of Al3Ni and Al2O3 particles increased with the number of FSP passes. The maximum surface microhardness of 253 HV is reached after 10 passes. As the number of FSP passes increases, the grain / subgrain sizes of the aluminum matrix decrease. After 10 passes, the grain / subgrain sizes stabilize at a level of 0.8 – 0.9 μm.