The coupling influences and corresponding mechanisms of high efficiency thermal-magnetic treatments on the dimensional stability of Al-Cu-Mg alloy

Al-Cu-Mg alloys are widely utilized as a key component of gyroscope navigation systems, since their dimensional stability under different service environments (e.g., thermal or magnetic fields) is the determinant factor for reliable navigation. In this work, a preliminary treatment under the coupling of thermal-magnetic fields was applied to optimize the dimensional stability of the alloy by tailoring the microstructural defects and second phases. A lower thermal strain value of ∼1.58 × 10–3 was rapidly achieved after 6 h by high-efficiency thermal-magnetic treatments (523 K and B = 0.3 T), in comparison with ∼1.67 × 10–3 by thermal treatment. The dimensional variation was mainly attributed to the dislocation density, volume fraction and shape of the Al2CuMg phase. Furthermore, the nucleation rate of Al2CuMg phases and the annihilation of dislocations were promoted under the coupling effect of the thermal-magnetic treatments. These microstructural evolutions accelerated the reduction of the stored energy and lattice distortion, therefore rapidly decreasing the thermal strain. As a result, a thermal-magnetic field treatment may serve as an effective method to improve the dimensional stability of Al-Cu-Mg alloys for further application in the field of space exploration.