The conventional peak-ageing treatment of friction-stir welded AA2519 resulted in precipitation of a stable θ-phase instead of the expected strengthening dispersoids of θ″ and θ′ thus degrading material strength. This phenomenon was attributed to acceleration of the precipitation kinetics due to grain refinement and over-ageing effect associated with the weld thermal cycle.

中文翻译：

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搅拌摩擦焊接Al–Cu–Mg合金的异常时效行为

搅拌摩擦焊接AA2519的常规峰值时效处理导致析出稳定的θ相，而不是预期的强化弥散体θ''和θ'，从而降低了材料强度。这种现象归因于由于晶粒细化和与焊接热循环相关的过时效效应而导致的沉淀动力学加速。