Characterisation and Investigation of Laser Sintered Pre-alloyed NiTi

摘要

The production of shape memory alloys of NiTi, using powder metallurgy methods, instead of a melting process offers several advantages. Namely, grain growth and segregation can be avoided. This near-net-shape process provides a cost effective solution, by substituting the expensive machining after casting. In this study laser sintering is used to consolidate bulk samples from powder of the near equiatomic alloy NiTi. The alloyed powder has been produced by a novel, innovative and cost-effective technique. Different initial particle sizes for the feed powder ranging from 20 to 80 μm were investigated and it is possible to achieve a homogeneous solid component with a density of approximately 99% for particles between 40 and 60 μm. The microstructure and internal stress is directly correlated to the initial powder and the production process. An improvement of the shape memory effect in the bulk material was achieved via a post heat treatment.