Use of 4D-printing and shape memory alloys to fabricate customized metal jewels with functional properties

Purpose This paper aims to examine customized NiTi jewels with functional properties fabricated through four-dimensional (4D)-printing. Design/methodology/approach Two opened rings are fabricated through selective laser melting starting from 55.2Ni-Ti (wt.%) micrometric powder. After the additive process the two rings present the one-way shape memory effect (OWSME). A specific training is accomplished on one of the two printed rings to promote the two-way shape memory effect (TWSME). Both the samples, namely, the rings, respectively, presenting the OWSME and TWSME property, follow a series of post-processing routes to improve the surface finish. Furthermore, a thermal treatment at high temperature is used to create a thin colored oxide layer on the sample surface. Findings Results show that the change of shape owing to the OWSME and TWSME properties allows the customized 4D-printed rings to be adaptable to environmental changes such as load and temperature variations. This adaptability improves comfort and fit of the jewels. Originality/value To the best of the authors' knowledge, in this work, first cases of additively manufactured NiTi jewels are reported to propose innovative solutions in the design and processing industry of jewels.