With the increase of time, the shrinkage of materials at fixed temperature could enhance the failure of fasteners. We report a potential way to alter the volume/length of alloy automatically through isothermal aging due to pseudospinodal decomposition mechanism. The volume of Ti-10V-2Fe-3Al alloy first shrunk and then expanded during isothermal aging at 550 degrees C. It can fit tightly and make up for volume loss. Transmission electron microscopy observation exhibits no obvious coarsening of intragranular alpha phase with the increasing time. However, composition evolution with time shows a gradual change through energy dispersive spectrometer analysis. The result shows that beta stabilizers, V and Fe, are prone to diffuse to the beta matrix, while alpha stabilizers, Al, prefer to segregate to the alpha phase. First principle calculations suggest that the structure transition for beta to alpha cause the first decrease of volume, and the diffusion of V, Fe and Al is the origin of the later abnormal increase of volume.