压缩预变形对7050铝合金非等温时效析出行为的影响

Effect of compressed pre-deformation onprecipitation behavior of 7050 aluminumalloy during non-isothermal aging

采用TEM,DSC等技术表征压缩预变形条件下7050铝合金升温时效的析出行为,并研究变形量对升温时效析出的影响规律和机制。结果表明:7050铝合金通过预变形升温时效后能够获得良好的强度及耐蚀性,并且比传统时效工艺明显缩短时间,能够有效降低能耗。预变形极大促进了7050铝合金的时效析出,在相同升温时效过程中析出相的尺寸及尺寸分布范围随着变形量提高而迅速增大。升温时效过程中预变形不仅能够降低7050铝合金η′,η相的相变激活能,而且可以加速溶质原子的扩散,因此加剧了Ostwald熟化,促进析出相的长大。计算结果显示,7050铝合金的相变激活能随着变形量的提高逐渐降低。当变形量从0%升高到18%时,η′,η相的相变激活能分别从116.0,120.8 kJ/mol降低到101.7,107.5 kJ/mol。

TEM,DSC and other techniques were used to characterize the heating aging precipitation behavior of 7050 aluminum alloy under compression pre-deformation conditions,and the influence law and mechanism of pre-deformation on heating aging precipitation were investigated.The results show that 7050 aluminum alloy can obtain excellent strength and corrosion resistance after pre-deformation heating aging,which can significantly shorten time and reduce energy consumption compared with traditional aging process.The pre-deformation greatly promotes the aging precipitation of 7050 aluminum alloy.The precipitate size increases rapidly as the increase of deformation during the same heating aging process,and its size distribution range increases rapidly too.The pre-deformation during heating aging process not only reduces the phase transformation activation energy ofη′andηphases of 7050 aluminum alloy,but also accelerates the diffusion of solute atoms,which intensifies the Ostwald ripening and promotes the growth of precipitates.The calculation results show that the phase transformation activation energy of 7050 aluminum alloy gradually decreases with the increase of deformation.When the deformation amount increases from 0%to 18%,the phase transition activ-ation energy ofη′andηphases decreases from 116.0 kJ/mol to 101.7 kJ/mol and 120.8 kJ/mol to 107.5 kJ/mol,respectively.