Nonhysteretic metamagnetic phase transition in Ho2In1-xAlx (0 ≤ x ≤ 0.4) by hetero-structural alloying

•The hexagonal structure observed for x ≤ 0.1 while orthorhombic one for ≥ 0.2.•The first-order-like phase transition is observed near critical composition of x = 0.1.•The largest ΔSmax of 16.3 Jkg-1K−1 and ΔTad of 6.5 K is realized by a nonhysteretic metamagnetic phase transition.•Improved performance is contributed from the enhanced magnetoelastic coupling.•It is explained by the delocalized Ho 5d electrons and further proved by the increased ΔR/R in Ho2In0.9Al0.1 alloy.