Die-upset magnets from a mechanically-milled Pr(Co,In)₅-type alloy are known to have a peculiar texture; the
easy magnetization axis (c-axis) is perpendicular to the pressing direction. This peculiar texture is thought to be linked closely to the anisotropic mechanical properties of Pr(Co,In)₅-type hexagonal compounds. The hardness of the Pr(Co,In)5-type crystal was measured using selectively grown grains in an annealed Pr₁₇Co₈₂In1 alloy button, and the crystallographic orientation was determined by observing the magnetic domain image. The hardness (549 VHN) on the plane with a ‘cogwheel’-type domain image was significantly higher than that (510 VHN) on the plane with a ‘cigar’-type domain image, indicating that the inter-layer bonding force between the (000l) basal planes is stronger than that between the (hki0) planes. This suggests that the most probable slip plane is the (hki0) plane parallel to the c-axis. During die-upsetting of the Pr(Co,In)₅-type alloys the deformation proceeds by (hki0) plane slip, and the c-axis rotates to ultimately become oriented perpendicular to the pressing direction. It is proposed that the peculiar texture in the die-upset Pr(Co,In)₅-type magnets is probably developed by slip deformation of the (hki0) plane of the Pr(Co,In)₅-type grains.