Quenched elinvar alloy 45NKhT has a decreased Young's modulus, which may be restored by aging, bringing the alloy to a more equilibrium state. The anomalous deviation of Young's modulus from the equilibrium value may be divided into the magnetoelastic and structural components, which originate from ferromagnetic ordering and structural instability, respectively. The thermoelastic coefficient γ of the alloy is characterized by a substantial aging-temperature dependence, which allows one to control the degree of elinvar anomaly manifested by the alloy.