Study of the heat capacity of VZhM4 nickel superalloy using differential scanning calorimetry, adiabatic and mixing calorimetry

An increase in the operating temperatures of assemblies and parts of modern aircraft is a key task for the aviation industry which entails developing of new materials that meet the increased requirements for their operational characteristics. A high level of the accuracy and reliability of the determined properties is one of the most important factors in designing high-temperature metal, ceramic and heat-shielding materials. The features of a particular measurement procedure, as well as their hardware design, do not always ensure the specified accuracy of experiments over the entire temperature range. We present the results of studying the heat capacity of VZhM4 nickel superalloy in the temperature range 100 – 1360° C by the methods of differential scanning calorimetry (DSC), adiabatic and mixing calorimetry. The data of the DSC analysis of the alloy, the temperatures of phase transformations and temperature dependences of the specific heat of the material are analyzed along with the assessment of their accuracy at different temperature intervals. A comparative analysis of the studied measurement procedures complements the research. The results obtained can be used in the development of new materials and in the study of the specific heat capacity of metal products in a wide temperature range.

The Influence of Pd and Zr Co-Doping on the Microstructure and Oxidation Resistance of Aluminide Coatings on the CMSX-4 Nickel Superalloy

Pd + Zr co-doped aluminide coatings were deposited on the CMSX-4 nickel superalloy, widely used in the aircraft industry, in order to investigate their microstructure and improvement of oxidation resistance. Palladium was deposited by the electrochemical method, whereas zirconium and aluminum by the chemical vapor deposition (CVD) method. Coatings consist of two zones: the additive and the interdiffusion one. The additive zone contains β–(Ni,Pd)Al phase with some zirconium-rich precipitates close to the coating’s surface, whereas the interdiffusion zone consists of the same β–(Ni,Pd)Al phase with inclusions of refractory elements that diffused from the substrate, so called topologically closed-packed phases. Palladium dissolves in the β–NiAl phase and β–(Ni,Pd)Al phase is being formed. Pd + Zr co-doping improved the oxidation resistance of analysed coatings better than Pd mono-doping. Mechanisms responsible for this phenomenon and the synergistic effect of palladium and zirconium are discussed.

Statistical Analysis and Optimisation of Data for the Design and Evaluation of the Shear Spinning Process

This work proposes a research method that is a scheme that can be universally applied in problems based on the selection of optimal parameters for metal forming processes. For this purpose, statistical data optimisation methods were used. The research was based on the analysis of the shear spinning tests performed in industrial conditions. The process of shear spinning was conducted on the components made of Inconel 625 nickel superalloy. It was necessary to select the appropriate experimental plan, which, by minimising the number of trials, allowed one to draw conclusions on the influence of process parameters on the final quality of the product and was the starting point for their optimisation. The orthogonal design is the only design for three factors at two levels, providing non-trivial and statistically significant information on the main effects and interactions for the four samples. The samples were analysed for shape and dimensions using an Atos Core 200 3D scanner. Three-dimensional scanning data allowed the influence of the technological parameters of the process on quality indicators, and thus on the subsequent optimisation of the process, to be determined. The methods used proved to be effective in the design, evaluation and verification of the process.