Coherency strains that arise during natural aging can substantially affect the material properties of Al alloys. Yet, these time-dependent phase transformations must be precisely distinguished from the immediate results of quenching after solution treatment. In this study, automotive B319 Al castings with varying solidification rates and strontium contents were subjected to solution treatments at 500 °C for up to 48 hour. Their hardness and electrical conductivity were measured as-quenched and again after 7 days at ambient-temperature. The role of Cu segregation and growth was effectively isolated from the Cu dissolution and Si spheroidization processes that occurred during the prior high-temperature treatment. The evolution of coherent Cu zones in the Al lattice within 10 hour of natural aging was sufficient to reach stable, 20 to 30 pct improvements in alloy hardness, relative to the as-cast and as-quenched conditions. However, the increased coherency strains from natural aging were detrimental to conductivity, promoting 1 to 1.5 pct IACS reductions from the as-quenched values, independent of the casting prehistory. These insights provided a clear understanding of the mechanisms controlling mechanical properties and electron flow in B319 alloy, and they elucidated the relative magnitudes of solid solution and coherency strains. These observations are critical for improving Al alloy heat treatment procedures.

自然时效过程中产生的相干应变会严重影响铝合金的材料性能。但是，必须将这些与时间有关的相变与固溶处理后立即淬灭的直接结果区分开。在这项研究中，具有不同凝固速率和锶含量的汽车B319 Al铸件在500°C下进行了长达48小时的固溶处理。淬火后测量它们的硬度和电导率，并在环境温度下7天后再次测量。从先前的高温处理过程中发生的Cu溶解和Si球化过程中，有效地分离了Cu偏析和生长的作用。自然老化10小时内，Al晶格中相干Cu区的演变足以达到稳定，相对于铸态和淬火条件，合金硬度提高20至30％。然而，由于自然时效而增加的相干应变对导电性是有害的，与铸造前的值无关，与所测得的值相比，使IACS降低了1至1.5 pct，降低了IACS。这些见解提供了对控制B319合金机械性能和电子流的机理的清晰理解，并且阐明了固溶体和相干应变的相对大小。这些观察对于改进铝合金热处理程序至关重要。独立于铸造史前史。这些见解提供了对控制B319合金机械性能和电子流的机理的清晰理解，并且阐明了固溶体和相干应变的相对大小。这些观察对于改进铝合金热处理程序至关重要。独立于铸造史前史。这些见解提供了对控制B319合金机械性能和电子流的机理的清晰理解，并且阐明了固溶体和相干应变的相对大小。这些观察对于改进铝合金热处理程序至关重要。