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

Purpose - In this work, 4D-printing is used to fabricate customized NiTi jewels with functional properties. 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 two 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 due 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 - In this work, first cases of additively manufactured NiTi jewels are reported in order to propose innovative solutions in the design and processing industry of jewels.