A high-specific-strength and corrosion-resistant magnesium alloy

1、A high-specific-strength and corrosion-resistant magnesium alloyUltra-lightweight alloys with high strength, ductility and corrosion resistance are desirable for applications in the automotive, aerospace, defence, biomedical, sporting and electronic goods sectors. Ductility and corrosion resistance

2、are generally inversely correlated with strength, making it dicult to optimize all three simultaneously. Here we design an ultralow density (1.4g/cm3) MgLi-based alloy that is strong, ductile, and more corrosion resistant than Mg-based alloys reported so far. The alloy is Li-rich and a solute nanost

3、ructure within a body-centred cubic matrix is achieved by a series of extrusion, heat treatment and rolling processes. Corrosion resistance from the environment is believed to occur by a uniform lithium carbonate film in which surface coverage is much greater than in traditional hexagonal close-pack

4、ed Mg-based alloys, explaining the superior corrosion resistance of the alloy.AbstractMethods1. The magnesium alloy contains (at.%/wt%) 30.30/10.95Li, 2.34/3.29Al, 0.039/0.19Zrand 0.128/0.59Y.2. Samples were heat treated in a muffle furnace at temperatures up to 400 C for times ranging from 5 to 12

5、min, followed by cold water quenching. Ageing experiments were carried on the WQ alloy at temperatures ranging from 20 to 100 C for times of 1 min to 720 h. Cold-rolled plates of the alloy, 3mm in thickness, were solution treated for 5 min at 380 C, water quenched and aged for 3 h at 70 C, followed

6、by cold rolling in a two-high laboratory rolling mill to15-90% reduction.3. Optical microscopy was carried out on samples after the various stages of processing.4. X-ray diffraction (XRD) experiments were carried out on the MgLi alloy to investigate both the phases present and fine-scale structural

7、changes during various stages of processing.Methods5. Electrochemical and corrosion testing was carried out at room temperature inquiescent 0.1M NaCl (pH 6).6. Mass loss and hydrogen collection was conducted on the same specimens inparallel.7. Vickers hardness testing was carried out along the centr

8、al rolling plane of eachsample, using a load of 1 kg and 15 s loading time.A multidimensional property profileExt-extrudeWQ-water quenching WQA- water quenching,low-temperature ageingWQAR- water quenching,low-temperature ageing, cold rollingFigure 1 Optimization of the strengthductilitycorrosion pro

9、perty profile of the MgLi alloyFigure 2 Effect of thermal and mechanical treatment on hardness and corrosion susceptibilityStructural origin of the property profileFigure 3 Key structural changes in the MgLi alloy during various stages of processingFigure 4 Corrosion behaviour and the protective surfa