(華南理工大學 機械與汽車工程學院，廣州 510640)
摘 要: 采用拉伸性能測試、光學顯微鏡、掃描電鏡、透射電鏡、電子探針、X射線衍射等研究了T7熱處理態(tài)的擠壓鑄造Al-5.0Cu-0.6Mn-1.0Fe-1.0Ni合金的顯微組織及力學性能，重點研究了擠壓壓力對合金高溫力學性能的影響。結果表明：當擠壓壓力從0 MPa增加到75 MPa時，合金的高溫力學性能明顯提高，但抗拉強度和屈服強度的增加值隨溫度升高而逐漸減小。擠壓壓力可以消除合金中的縮松，抑制合金中針狀Al7Cu2Fe相的形成，使塊狀Al7Cu2Fe相及Al9FeNi相分布更為彌散，并形成聯(lián)通的骨骼狀結構。但是，擠壓壓力也使合金晶間熱穩(wěn)定性好的富鐵相數量減少，同時，細化合金晶粒及二次枝晶，增加晶界數量。
關鍵字: 鋁銅合金；擠壓鑄造；高溫；力學性能
（School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China）
Abstract:The microstructures and mechanical properties of the T7 heat-treated Al-5.0Cu-0.6Mn-1.0Fe-1.0Ni alloy prepared by squeeze casting were studied by tensile test, optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe micro analysis (EPMA), X-ray diffraction analysis (XRD). The effect of applied pressure on the elevated temperature mechanical properties of the alloy was investigated mainly. The results show that the mechanical properties of the alloy at elevated temperatures are improved significantly when the applied pressure increases from 0 to 75 MPa. However, the increments of the ultimate tensile strength and yield strength decrease with the increase of the temperature. The applied pressure can eliminate the porosity and suppress the formation of needle-like Al7Cu2Fe phase. Meanwhile, the block-like Al7Cu2Fe and Al9FeNi phases become smaller and more dispersive and form the interconnected bone-like structure. Unfortunately, the applied pressure reduces the volume fraction of the thermo-stable iron-rich phases and it also refines the grain size and secondary dendrite arm space of the alloy, which leads to the increase of grain boundary.
Key words: aluminum-copper alloy; squeeze casting; elevated temperature; mechanical property
