Ti元素对7072铝合金显微组织与性能的影响

The Effects of Titanium Addition on Microstructure and Performances of 7072 Aluminum Alloy

通过透射电镜、扫描电镜、拉伸试验和电化学测试等方法,系统研究了Ti元素的添加对模拟钎焊态7072铝合金热传输材料的显微组织、不同条件下力学性能与电化学性能的影响规律.透射电镜分析表明,Ti元素的添加对晶粒尺寸的影响微弱,且对析出相的析出有抑制作用.力学试验结果表明,Ti元素对钎焊态合金的高温力学性能有很大的影响.常温下含Ti合金的拉伸力学性能与无Ti合金相近.但在150℃测试时,屈服强度可提高5.5 MPa,抗拉强度和延伸率基本不变.在200℃测试时,抗拉强度可提高近10 MPa,屈服强度和延伸率略有下降.电化学试验结果表明,添加Ti元素能提高钎焊态7072铝合金的抗腐蚀性能,可使7072铝合金在0.5%NaCl溶液、3.5%NaCl溶液和1M NaCl+0.3M H2O2溶液中的腐蚀电位分别正移8.3mV、11 mV和8.5 mV.

In the present work, the effect of Ti addition on the microstructure, mechanical properties and electrochemical properties of simulated-brazing 7072A1 alloy was investigated. Transmission electron microscopy （TEM） observations revealed that, in simulated-brazing state, there was no much difference in the grain size of the Ti-containing alloy and the Ti-free alloy and Ti-eontaining alloy had less dense precipitates. Tensile testing results indicated that the room-temperature tensile properties of Ti-containing alloy were close to those of Ti-free alloy. Ti addition could have great influence on the comprehensive mechanical properties of the simulated-brazing alloys tested at elevated temperatures. At 150℃ the yield strength increased by 5.5 MPa due to Ti alloying. Whereas, the tensile strength increased by nearly 10 MPa at 200 ℃. Electrochemical testing results revealed that, with Ti addition, the corrosion resistance of the simulated-brazing alloy was improved by showing a positive shift of the corrosion potential. In 0. 5% NaCl solution , 3.5% NaCl solution and 1M NaC1 ＋ 0. 3M H202 solution, corrosion potential increased by 8.3 mV, 11 mV and 8.5 mV, respectively.