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A combinatorial assessment of composition‐microstructure‐magnetic property relationships in magnetic high entropy AlCoxCr1‐xFeNi alloy (0 ≤ x ≤ 1) system has been carried out using compositionally graded alloys fabricated via laser additive manufacturing. At one end, the AlCoFeNi composition (x = 1) consisted of equiaxed B2 grains, exhibiting very early stages of phase separation (only compositional partitioning) into Ni–Al rich and Fe–Co rich regions within grains of the B2 phase. At the other extreme, the AlCrFeNi composition (x = 0) exhibited grains with pronounced spinodal decomposition, resulting in a B2 + bcc microstructure with the degree of spinodal decomposition progressively increasing with Cr content in these AlCoxCr1–xFeNi alloys. While the saturation magnetization (Ms) monotonically increases six times from x = 0 to x = 1, the coercivity (Hc) variation is non‐monotonic, increasing seven times from x = 0 to x = 0.4, and subsequently decreasing fourteen times from x = 0.4 to x = 1.0. The magnetic phase transition temperature (Tc) for these alloys also increases monotonically with increasing Co content with a second phase transition exhibited in a certain range of compositions between x = 0.6 to x = 0.8. Such substantial changes in the magnetization behavior and properties of magnetic high entropy systems opens possibilities of tuning these alloys for specific soft or hard magnetic component applications.

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Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100−xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg−1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

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