The microstructural evolution of Ni–42Ti–7Al and Ni–41Ti–7Al alloys as a function of solution and aging heat treatment was investigated using transmission electron microscopy(TEM), electron probe, and X-ray diffraction(XRD). The results reveal that the volume fraction of Ti2 Ni phase as well as its composition does not change significantly after as-solution treated at 1200 °C and aged at850 °C. At the early stage of the aging treatment at 850 °C for 1 h, the cuboidal b0 precipitate keeps coherency with the matrix; further aging, b0 precipitate coarsens, and the semicoherency between the b/b0 two phases are observed.The shape of coarsened b0 precipitates changes to the globule, and the interface dislocations are introduced accompanied by the occurrence of semicoherent precipitates. Under the same heat treatment, compared to the Ni–42Ti–7Al alloy, the lattice misfits of the Ni–41Ti–7Al alloy between the b and b0 two phases are larger, so the b0 precipitates in Ni–41Ti–7Al alloy are coarsened severely and easily lose coherency with the matrix. The thermal stability of Ni–41Ti–7Al alloy is much worse when aging at 850 °C. The microstructural evolution of Ni-42Ti-7Al and Ni-41Ti-7Al alloys as a function of solution and aging heat treatment was investigated using transmission electron microscopy (TEM), electron probe, and X-ray diffraction (XRD). The results reveal that the volume fraction of Ti2 Ni phase as well as its composition does not change significantly after as-solution treated at 1200 ° C and aged at 850 ° C. At the early stage of the aging treatment at 850 ° C for 1 h, the cuboidal b0 precipitate keeps coherency with the matrix; further aging, b0 precipitate coarsens, and the semicoherency between the b / b0 two phases are observed. shape of coarsened b0 precipitates changes to the globule, and the interface dislocations are described accompanied by the occurrence of Under the same heat treatment, compared to the Ni-42Ti-7Al alloy, the lattice misfits of the Ni-41Ti-7Al alloy between the b and b0 two phases are larger, so the b0 precipitates in Ni-41T i-7Al alloy are coarsely severely and easily lose coherency with the matrix. The thermal stability of Ni-41Ti-7Al alloy is much worse when aging at 850 ° C.