Data related to the research article "Microstructure and phase stability within the AlMoNbTiZr system: design tools and compositional boundaries for a high-entropy alloy" (preprint: http://arxiv.org/abs/2510.08417, version of record: https://doi.org/10.1016/j.jmrt.2025.09.118). The article figures were produced solely from these data sets employing data processing methods described therein. For experimental conditions and naming conventions please refer to the manuscript. 1. Alloy selection strategy, calculation of Bo-Md diagram (Fig. 1):The Fig1_Bo-Md_data.csv file contains 12 columns delimited by commas:First three columns are the elemental electronic paramters Md and Bo.Columns 4-5 are values to construct the Ms-RT line, empirically built and registered for traditional Ti alloys.Columns 6-10 contain the elemental composition of the four studied alloys.Finally, columns 11-12 are the average Bo and Md values calculated for the four studied alloy compositions. 2. High-resolution SEM images (related to Fig. 2) are available directly within the published article. The raw EDS mappings acquired are within the Figure 2 folder containing four subfolders:inset_a)_20Ti (with presented pictures in .tif and .csv files)inset_b)_25Ti (with presented picture in .tif and report area analysis in an .odt file)inset_c)_30Ti (with presented picture in .tif and report area analysis in an .odt file)inset_d)_35Ti (with presented picture in .tif and report area analysis in an .odt file) 3. The values of lowest enthalpies of formation of elemental couples in the AlMoNbTiZr system related to Fig.3 are listed in the "Figure3a.cvs" file, which contains 6 columns separated by commas, and each of them corresponds to the values of the Table displayed in this Figure's inset.The XRD patterns acquired for each of the alloys are in the subfolder named "XRD_patterns" in three files formats: .asc, .txt, and .raw, all of them including the 2-theta angle position and corresponding intensity in counts. The reference pattern files of each phase for comparison are included inside the subfolder "reference_phase_patterns" with generic name: "Chemical-composition-of-phase_crystal-structure.txt" or .rtf extension. 4. High-resolution TEM images (related to Fig. 4) are in the folder "raw_TEM_images_35Ti_alloy" and also available directly in the PDF and web version of the manuscript. SAED images (.bmp and .dm4 filetype) are inside the folder "Selected_area_electron_diffraction". The raw date for the EDS chemical quantification is provided in the eds_quant.txt file. 5. Files with microhardness data HEA_AlMoNbTiZr_TiXX.csv (where XX=sample designation by Ti content, in line with Fig. 5a in the manuscript) include columns with: Indentation number, Microhardness (HV 1.0), Real Indentation Position X [mm], and Real Indentation Position Y [mm], date & time of measurements; in the end of the files, there is a summary of initial values with the reported average and standard deviation from all measurements.Identation pics are inside the "Indentations_pics" folder, including the pictures with generic name TiXX_#.tif (where XX designates the Ti content and # is a link to the picture number).The files "Specimen_RawData_#.cvs" for Fig. 5b containing the raw compression data are inside the folder "Figure_5b_CompresionStress-StrainData". The files also include the dimensions of the specimens and the true stress, true strain data. 6. Empirical parameters calculated by HEAPS free-source calculator and original sources (see references in electronic manuscript) are listed in the file "Empirical_parameters_HEAPS_and_equations_from_primary_references.csv". These values were used in Fig. 6 and listed in Table 2 and Table 3 in the manuscript. 7. Files with the volume phase composition (Fig. 7) predicted by Thermocalc (database TCHEA4) are compiled under the general name "XXTi_volume_fraction_of_phases.txt" (where XX is the nomenclature of the alloys based on their Ti content), according to Figure 7 in the manuscript. 8. Files containing the phase prediction by Thermocalc (database TCHEA4) based on the elemental composition of each element with respect to Ti content at 1200 °C and 1300 °C for the 35Ti alloy are with general name "delta_element_phase_prediction_1200&1300C.csv", in agreement with Figure 8. 9. The file containing the simulated bcc-phase stability varying the Al-Mo-Zr composition for the 35Ti-alloy in accordance with Figure 9 is labeled as "delta_Al_&_Mo_over_Zr_bcc_stability_at_1300C.cvs" The bcc volume fraction is specified in row no. 3 of the file, while the columns include the variation of the at.% of Al, Mo, and Zr. For any further enquiry, please refer to authors of the paper.