Fe含量對擠壓鑄造Al-Cu合金組織演變及高溫力學(xué)性能的影響

Fe含量對擠壓鑄造Al-Cu合金組織演變及高溫力學(xué)性能的影響Effects of Fe content on microstructure evolution and elevated-temperature mechanical properties of squeeze cast Al-Cu alloys

采用拉伸性能測試、掃描電子顯微鏡(SEM)、透射電子顯微鏡(TEM)等研究Fe含量對擠壓鑄造Al-Cu合金組織演變及高溫力學(xué)性能影響。結(jié)果表明：隨著Fe含量的增大，鋁銅合金的常溫和高溫性能急劇下降，這主要是由于針狀富鐵相增多，同時鋁銅合金基體中強化相減少。而耐熱富鐵相可以一定程度上阻礙晶界高溫滑移，F(xiàn)e含量對合金高溫力學(xué)性能的影響沒有常溫性能那么敏感。擠壓壓力可以顯著提高合金的高溫性能，尤其是合金的伸長率，但與常溫力學(xué)性能相比，擠壓壓力對高溫力學(xué)性能的提升幅度下降。同時，擠壓鑄造鋁銅合金的高溫伸長率在Fe含量為0.5%(質(zhì)量分數(shù))的附近存在一個峰值。這主要是由于擠壓壓力下合金致密，富鐵相尺寸變得細小，針狀富鐵相大幅減少，同時晶粒細化導(dǎo)致高溫下晶界弱化加劇。

The effects of Fe content on the evolution of microstructure and elevated-temperature mechanical properties of squeeze cast Al-Cu alloys were studied by tensile test, scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results show that the room temperature and elevated-temperature mechanical properties decrease with increasing Fe content in Al-Cu cast alloys, which attribute to the increase of volume fraction of needle-like iron-rich intermetallics and the decrease of volume fraction of precipitation particles in α(Al) matrix. The heat-resistant iron-rich intermetallics phases around the grain boundary can prevent the sliding of grain boundary at elevated temperature. As a result, the effect of Fe content on elevated-temperature mechanical properties is less sensitive than room-temperature mechanical properties. The applied pressure improves the elevated temperature mechanical properties, especially the elongation. However, the increased range of elevated temperature mechanical properties resulted by applied pressure decreases compared to the room temperature mechanical properties, and there is a peak value of elongation at elevated temperature for the squeeze cast alloys with Fe content of 0.5% (mass fraction). The results attribute to the high dense-component of squeeze cast alloys, the refinement of iron-rich intermetallics, the decrease of needle-like iron-rich intermetallics, and the refinement of grain size which leaded to the weakness of grain boundary at elevated temperature.

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