The present paper investigates the influence of Nb on microstructures and functional properties of NiTiNb shape memory alloys (SMAs). It is first outlined why SMAs for coupling devices must be characterized by a wide peak to peak hysteresis defined as the difference between the martensite peak temperature in a differential scanning calorimetry (DSC) experiment on cooling and the corresponding austenite peak temperature on subsequent heating. It is then confirmed that adding Nb to NiTi does increase the width of the hysteresis from about 40degreesC for the stochiometric binary alloy to in between 57degreesC to 82degreesC for ternary NiTiNb alloys, with Nb contents ranging from 5 to 21 atomic percent. The evolution of microstructure during casting and subsequent thermo-mechanical treatments is then investigated for NiTiNb alloys with 9 and 21 atomic percent Nb using scanning electron microscopy (SEM). The corresponding phase transformation temperatures are measured using DSC. For the NiTiNb alloy with 9 atomic percent Nb it is shown how different thermo-mechancial treatments affect phase transformation temperatures.