Phase constitution, microstructure and load-dependent dry-sliding behaviour of a multiphase AlFeNiSiTi aluminide–silicide alloy

Nominally equiatomic AlFeNiSiTi was produced by horizontal plasma arc melting, and part of the material was subsequently remelted five times to evaluate the impact of different production methods on phase constitution, microstructure, mechanical properties, and dry-sliding behaviour. The alloy was characterised by X-ray diffraction with Rietveld refinement, SEM/EDS, EBSD, hardness testing, and instrumented indentation. Ball-on-disk tests against an Al 2 O 3 counterbody were performed at normal loads of 5, 10, and 20 N. Both conditions exhibited a three-phase intermetallic microstructure consisting of a B2-NiAl matrix with pronounced Fe substitution and orthorhombic FeSiTi and NiSiTi silicides. Remelting refined the dendritic morphology and shifted the relative balance of the identified silicide phases towards NiSiTi, while bulk hardness changed only slightly from 803 ± 13 to 826 ± 18 HV10. In contrast, the microhardness of the silicide regions increased from 1534 ± 23 to 1787 ± 55 HV0.01, and the indentation modulus increased from 121.8 ± 15.5 to 274.5 ± 18.5 GPa. For the arc-melted alloy, the specific wear rate increased with load from 4.90 × 10 −5 to 9.19 × 10 −5 mm 3 N −1 m −1 , accompanied by a transition from oxide-debris-assisted wear to severe abrasion with local plastic deformation. Remelting produced predominantly abrasive wear at all loads. Wear rates remained comparable at 5 and 10 N but increased by approximately 42% at 20 N, despite the lower friction coefficient at this load. The results show that remelting alters wear mechanisms and contact severity rather than consistently improving wear resistance.