Materials for impact applications require a unique combination of high hardness, high dynamic compressive strength, and reasonable toughness (i.e., suitable ductility). This paper presents the aging effects on the microstructural evolution, hardness, and compressive high-strain rate behavior of Ni-rich Ti–55Ni (at.%) alloy. Aging heat-treatments of Ti–55Ni between 400°C and 1000°C led to the following precipitation sequence: Ti 3 Ni 4 →T 2 Ni 3 →TiNi 3 . Among these, Ti 3 Ni 4 and T 2 Ni 3 were found to be metastable phases since they transformed to TiNi 3 phase during longer aging times or higher aging temperatures. Initial investigations were focused on precipitation studies to obtain a time–temperature–transformation (T–T–T) diagram for Ti–55Ni. High-strain rate compression tests and hardness studies indicated that significant strengthening by Ti 3 Ni 4 and Ti 2 Ni 3 precipitates was accompanied by very low failure strains, i.e., low ductility. However, precipitation of TiNi 3 during high-temperature aging led to a good balance between strength (1400–2000MPa) and ductility (10–20%).