A concise review of the applications of NiTi shape-memory alloys in composite materials Composite materials have increasingly been used in construction and in the aerospace and automotive industries because they are lightweight, strong and corrosion resistant, and because their anisotropic properties can be controlled; maintenance costs are also low. However, there is a growing demand for improved composite materials which have 'smart' capabilities, that is, they are able to sense, actuate and respond to the surrounding environment. Shape-memory alloys (SMAs) possess sensing and actuating functions. Embedding SMAs into composite materials can create smart or intelligent composites. Amongst the commercially available SMAs, NiTi alloys-in the form of wires, ribbons or particles-are the most widely used because of their excellent mechanical properties and shape-memory performance. These materials have found application in broad fields of engineering and science as a result of their superior thermomechanical properties. Here we review the use of NiTi SMAs in applications such as vibration control, shape control, position control and adaptive stiffening. General properties of NiTi shape-memory alloys NiTi SMAs can exist in two crystal phases: (1) the stronger austenite (or parent) phase which is stable at high temperatures and (2) the softer martensite (product) phase which is stable at low temperatures. 7 The NiTi SMA in its martensitic phase can be easily deformed because of its relative softness. The austenite phase has a well-ordered body-centred cubic structure that presents only one variant. The martensite phase has a lower symmetry and may exist in multiple variants depending on the type of phase transformation. Therefore, although there are several ways by which martensite can be formed out of austenite, there is only one route by which the martensite formed will revert to austenite. The understanding of the characteristics of NiTi SMAs such as SME and pseudoelasticity, is important in the design and implementation of NiTi-based devices.