过饱和ZAC27合金的阻尼性能与组织演变

Damping capacities of supersaturated ZAC27 alloy and its relation with microstructural evolution

研究了过饱和ZAC2 7合金在自然时效过程中的组织演变与其阻尼性能的关系。过饱和ZAC2 7合金时效1d后 ,组织中出现了大量的 η相、α相和少量的ε相。随时效时间的延长 ,η相、α相和ε相的量越来越多 ,时效 10d后 ,β相已分解完全并消失。此后各相进一步粒化、聚集 ,在 5 0d后形成了较粗大的、由近似等轴的短棒状的α相、η相和ε相组成的平衡组织。过饱和ZAC2 7合金在自然时效过程初期 ,阻尼性能迅速而明显地提高 ,在时效第 10d时声频阻尼性能达到最高值 ,约为 7× 10 -3 ;随后阻尼性能缓慢下降 ,5 0d后基本稳定不变 ,稳定后的阻尼性能约为4× 10 -3 。过饱和ZAC2 7合金的阻尼来源于界面阻尼和位错阻尼 ,η相和ε相从过饱和ZAC2 7合金中的脱溶以及溶质原子和淬火空位与位错的交互作用是过饱和ZAC2 7合金阻尼性能产生变化和提高的主要原因。ZAC2 7合金均匀化热处理及自然时效是一种很好的提高阻尼性能的热处理工艺。

The microstructural evolution of supersaturated ZAC27 alloy and its damping capacities were investigated systematically in the period of natural ageing. The investigation shows that the microstructure of ZAC27 alloy evolves as follows: after 1 day ageing, α phase, η phase andε phase appear in the alloy, moreover, the amount of α phase, η phase and ε phase increase with the increasing of ageing time; after 10 d ageing, the β phase decomposes and vanishes completely in the alloy; after 50 d ageing, phases gather and form the coarser equilibrium microstructure which consists of near equiaxed, shot club shaped α, η and ε phase. Microstructure changes accompany with the variance of damping capacity. It is found that the damping capacities varies quickly and obviously during natural ageing. The damping capacity reaches the highest value 7×10 -3 at the 10th day. Sequentially, the damping capacity decreases gradually, and reaches a constant value of 4×10 -3 after 50 d natural ageing. The damping behavior in supersaturated ZAC27 alloy comes from a superposition of two mechanisms: interface damping and dislocation damping. The reasons for the great change of damping capacity of supersaturated ZAC27 alloy are as follows: 1) the precipitation of η and ε phases from supersaturated β solid solution and 2) the interaction of dislocation with vacancies and solute atoms. The results also indicate that solid solution+water quenching+natural ageing is the best heat treatment technique to improve the damping capacity of the ZAC27 alloy substantially. [