  Due to their versatile composition and customizable properties, A$_2$BC
Heusler alloys have found applications in magnetic refrigeration, magnetic
shape memory effects, permanent magnets, and spintronic devices. The discovery
of all-$d$-metal Heusler alloys with improved mechanical properties compared to
those containing main group elements, presents an opportunity to engineer
Heuslers alloys for energy-related applications. Using high-throughput density
functional theory calculations, we screened magnetic all-$d$-metal Heusler
compounds and identified 686 (meta)stable compounds. Our detailed analysis
revealed that the inverse Heusler structure is preferred when the
electronegativity difference between the A and B/C atoms is small, contrary to
conventional Heusler alloys. Additionally, our calculations of Pugh ratios and
Cauchy pressures demonstrated that ductile and metallic bonding are widespread
in all-$d$-metal Heuslers, supporting their enhanced mechanical behaviour. We
identified 49 compounds with a double-well energy surface based on Bain path
calculations and magnetic ground states, indicating their potential as
candidates for magnetocaloric and shape memory applications. Furthermore, by
calculating the free energies, we propose that 11 compounds exhibit structural
phase transitions, and propose isostructural substitution to enhance the
magnetocaloric effect.
