Multi-component high-entropy alloys (HEAs) with compositionally disordered elemental arrangement have attracted extensive attention because of their excellent mechanical properties. However, these alloys usually exhibit low strength at elevated temperatures. Recent works suggest that HEAs strengthened by L12 ordered intermetallics of the Ni3Al type possess a superior synergy of strength and ductility. The performance of such ordered-intermetallics-strengthened HEAs depends critically on the composition and deformation mechanism of the strengthening component, which will inevitably suffer partial disorder in HEAs. Here we will present our results on defect properties and deformation mechanisms of a series of L12-type (Ni,Co,Fe)3(Al,Ti,Fe) and its derived subsystems. We show that the partial disorder has significant influence on the properties of these ordered intermetallics. These results pave the way for rationally designing ordered-precipitate-strengthened HEAs.