A detailed computational investigation of 55-atom PdN\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{\varvec{N}}$$\end{document}Ag42-N\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{\varvec{42-N}}$$\end{document}Ni13\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$_{\varvec{13}}$$\end{document} Mackay-icosahedral nanoalloys is presented, combining Gupta-potential Basin-Hopping, spin-polarized DFT, local virial stress mapping, and finite-temperature molecular dynamics (MD). Chemical-ordering optimizations reveal that Ag preferentially occupies vertex sites while Pd populates edges and subsurfaces, yielding composition-dependent mixing energies that remain unfavorable up to N approximate to 8\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varvec{N\approx 8}$$\end{document} at the DFT level. Local pressure maps show anomalous surface compression and tensile subshells in Ag-rich clusters (Ni-Ag mismatch approximate to 16%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varvec{\approx 16\%}$$\end{document}) and conventional compressive-core/tensile-shell distributions in Pd-rich clusters (Ni-Pd mismatch approximate to 10%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\varvec{\approx 10\%}$$\end{document}). Melting-dynamics analyses indicate sharp transitions with no pre-melting surface rearrangements. The anomalous pressure distribution in Ag-rich compositions lowers their thermal resistance, resulting in melting at significantly lower temperatures than Pd-rich clusters, which maintain conventional stress profiles and higher thermal stability. Spin-polarized DFT confirms Ni atoms carry the dominant local magnetic moments, governed by coordination rather than local stress. Alternative Bergman-shell variants were also tested, demonstrating that a 32-atom shell restores the expected compressive-core/tensile-shell stress pattern.