The eta phase is an intermetallic particle with an hcp (hexagonal close-packed) structure, of the form Ni3Ti.  It has a plate-like morphology, and is stable in iron-nickel and iron-nickel-cobalt alloys.  It is a strengthening phase, but less effective than the gamma prime phase (Ni3Al).

Why do you want to know the properties of the eta phase by itself?  Intermetallic particles are extremely tiny, with diameters around 10 micrometers or less, and their influence on bulk mechanical properties is a complex situation based on size, morphology, orientation, degree of lattice disregistry, etc.  In order to obtain information on the mechanical properties of Ni3Ti, a bulk sample would need to be created, which will bear little resemblance to the plate-like particles present in superalloys.