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<p>To address the coarse microstructure inherent in cast Al–Cu alloys, we are using a new synergistic processing of ultrasonic power (UP) (300–900&#xa0;w) and squeeze cast (SC) (50&#xa0;MPa) to eliminate it by using optical microscopy, scanning electron microscopy, electron probe microanalysis (EPMA), and synchrotron radiation X-ray microtomography (SRXCT) to study the evolution of microstructure and properties. Results demonstrated that the application of UP and SC significantly refined the <i>α</i>-Al grains. As UP increased, the morphology of the <i>θ</i> (Al<sub>2</sub>Cu) phase transitioned from a coarse, interconnected network to fine discrete granular structures. Specifically, SRXCT analysis revealed that high ultrasonic power (900&#xa0;w) disrupted the spatial continuity of Al<sub>2</sub>Cu, resulting in isolated particles with increased mean curvature and reduced local thickness. EPMA confirms the enhancement of Cu solubility in the <i>α</i>-Al matrix, thus resulting in the reduction of the second-phase volume. This synergistic composite field yielded superior mechanical performance, with the UP+SC process increasing Rockwell hardness by 9.31&#xa0;pct (from 61.2 to 66.9&#xa0;HRF), which substantially surpassed the 5.49&#xa0;pct improvement observed in gravity casting. These enhancements are attributed to coupled mechanisms: ultrasonic cavitation fragments Al dendrites, acoustic streaming homogenizes solute distribution, and squeeze pressure eliminates porosity. This study confirms the efficacy of the UP+SC process in optimizing 3D phase morphology and enhancing the overall performance of Al–Cu alloys.</p>

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Mechanism of Ultrasonic Power and Pressure Synergistic Regulation of Microstructure and Mechanical Properties of Al–5.0Cu–0.6Mn Alloy

  • 期刊论文

  • 发表日期：

    2026年3月18日

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  • Jiahao Lai,
  • Jianjun Zhong,
  • Jiayun Niu,
  • Jianyu Long,
  • Jincheng Sun,
  • Weiwen Zhang,
  • Yuliang Zhao

摘要

To address the coarse microstructure inherent in cast Al–Cu alloys, we are using a new synergistic processing of ultrasonic power (UP) (300–900 w) and squeeze cast (SC) (50 MPa) to eliminate it by using optical microscopy, scanning electron microscopy, electron probe microanalysis (EPMA), and synchrotron radiation X-ray microtomography (SRXCT) to study the evolution of microstructure and properties. Results demonstrated that the application of UP and SC significantly refined the α-Al grains. As UP increased, the morphology of the θ (Al2Cu) phase transitioned from a coarse, interconnected network to fine discrete granular structures. Specifically, SRXCT analysis revealed that high ultrasonic power (900 w) disrupted the spatial continuity of Al2Cu, resulting in isolated particles with increased mean curvature and reduced local thickness. EPMA confirms the enhancement of Cu solubility in the α-Al matrix, thus resulting in the reduction of the second-phase volume. This synergistic composite field yielded superior mechanical performance, with the UP+SC process increasing Rockwell hardness by 9.31 pct (from 61.2 to 66.9 HRF), which substantially surpassed the 5.49 pct improvement observed in gravity casting. These enhancements are attributed to coupled mechanisms: ultrasonic cavitation fragments Al dendrites, acoustic streaming homogenizes solute distribution, and squeeze pressure eliminates porosity. This study confirms the efficacy of the UP+SC process in optimizing 3D phase morphology and enhancing the overall performance of Al–Cu alloys.