Oxidation resistance of Mg–9Al–1Zn alloys micro-alloyed with Be

Tan, Qiyang; Mo, Ning; Jiang, Bin; Pan, Fusheng; Atrens, Andrej; Zhang, Mingxing

doi:10.1016/j.scriptamat.2015.12.022

Cited by 46 publications

(30 citation statements)

References 21 publications

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“…Thus, the formation of SrO is significantly promoted after melting. In the case of Be, even though the solute solubility of Be in Mg is almost zero [169], a Mg-0.15Be alloy exhibits an ignition temperature of 750 C [198]. Furthermore, microalloying of Mg-Ca alloy with Be produced a significantly higher ignition temperature of 1050 C [165] as shown in Table 2.…”

Section: Discussion On Ignition Temperaturementioning

confidence: 99%

“…Alloying with 60 ppm (wt) Be extended the incubation period of AZ91 from 150 min to over 300 min.Fig. 25presents the oxidation data of Cheng et al[111] and Tan et al[169] for AZ91-1.5Ca, AZ91-1.5Ca-0.5Y, AZ91-20 ppm (wt) Be and AZ91-60 ppm (wt) Be at 400 C in air. AZ91 containing 20 ppm (wt) Be showed a lower oxidation rate than that of AZ91-1.5Ca.…”

mentioning

confidence: 90%

“…More recently, Tan et al [169] studied the oxidation resistance in the solid state of AZ91 micro-alloyed with Be. The oxidation weight gain at 400 C was reduced with increasing Be content from 10 ppm (wt) to 60 ppm (wt), indicating an increase in oxidation resistance.…”

Section: Bementioning

confidence: 99%

“…In addition, Tan [169] claimed that a continuous BeO layer did not exist based on the thermodynamic calculation and EDS results. Unfortunately, there was no mechanism studies.…”

Section: Bementioning

confidence: 99%

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Oxidation of magnesium alloys at elevated temperatures in air: A review

et al. 2016

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Highlights The oxidation behaviours of Mg alloys from low to high temperatures are reviewed. Characteristics of MgO during oxidation is discussed. Mechanisms of Mg oxidation is presented. Effect of various alloying elements is analysed. AbstractThis paper reviews (i) the oxidation of Mg alloys at elevated temperatures in air; (ii) the influence of alloying elements on the oxidation of Mg alloys; and (iii) the progress in the development of oxidation-resistant Mg alloys. Low oxidation rates have been shown by Mg alloys containing the alloying elements, Ca, Be and rare earth elements. However, these alloying elements may also decrease mechanical properties, such as ductility.

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Section: Discussion On Ignition Temperaturementioning

confidence: 99%

mentioning

confidence: 90%

Section: Bementioning

confidence: 99%

“…In addition, Tan [169] claimed that a continuous BeO layer did not exist based on the thermodynamic calculation and EDS results. Unfortunately, there was no mechanism studies.…”

Section: Bementioning

confidence: 99%

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Oxidation of magnesium alloys at elevated temperatures in air: A review

et al. 2016

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“…Unfortunately, the actual mechanism about how the Be supressed the Mg evaporation was not discussed. More recently, Tan et al [169] studied the oxidation resistance in the solid state of AZ91 microalloyed with Be. The oxidation weight gain at 400 C was reduced with increasing Be content from 10 ppm (wt) to 60 ppm (wt), indicating an increase in oxidation resistance.…”

Section: Be L Mgo S Beo S Mg L 15mentioning

confidence: 99%

Influence of trace addition of Be on the oxidation behaviour of Mg alloys

Tan¹

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As the lightest structural metallic materials, magnesium (Mg) alloys have attracted increasing interest in the automotive and aerospace industries. However, low oxidation resistance of Mg alloys limits their wider applications at elevated temperatures. Beryllium (Be) has long been considered as one of the most effective alloying elements in improving the oxidation resistance of Mg alloys even at ppm concentration. However, a convincing mechanism of this unique effect of Be in Mg alloys still remains unclear. Two mechanisms have been proposed. The BeO hypothesis assumes that the BeO layer forms prior to the MgO, whereas the reactive element effect model considers that the segregation of Be 2+ cations along the MgO grain boundaries inhibits the outward diffusion of Mg 2+ cations. Both models have never been experimentally verified. The present work aims to comprehensively investigate the effects of trace additions of Be on the high temperature oxidation behaviour of Mg alloys and, therefore, to understand the mechanism of how Be improves the oxidation resistance of Mg alloys.Be-containing AZ91 alloys were produced with trace additions of Be (10 ppm-60 ppm) into the alloy melt. Thermogravimetric analysis (TGA) and long-term furnace oxidation (LTFO) were used to characterize the oxidation behaviours of the alloys. All results showed that trace additions of Be significantly improved the oxidation resistance of the AZ91 alloy at 400 C, even at 10 ppm. In order to investigate the effectiveness of Be in other Mg alloys, 60 ppm Be was added to Mg-2Zn, Mg-2Sn, Mg-2Y, AS21, AM60, ZK20 and ZC63. Similar to the AZ91 alloy, experimental results showed that microalloying with Be effectively lowered the oxidation rates at 500 C and increased the ignition temperatures of the Mg-2Zn, Mg-2Sn, AS21, and ZC63 alloys. But, Be addition marginally influenced the oxidation behaviours of the ZK20, AM60 and Mg-2Y alloys.In order to understand the mechanisms behind why Be improves the oxidation resistance of cast Mg alloys, the oxidation layers were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation. No continuous BeO surface layers were observed on the surfaces of the alloys tested and no Be segregation was detected along the grain boundaries of MgO. However, TEM examination detected the accumulation of Be in the initially formed MgO layer during the oxidation process, which led to the formation of fine-grained (Mg,Be)O solid solutions. As a result, the initially formed surface oxide was effectively strengthened. The nanoindentation and nanoscratch analyses verified that the reinforced (Mg,Be)O layers on the Becontaining AZ91, Mg-2Zn, Mg-2Sn, AS21 and ZC63Be alloys exhibited a higher hardness and strength than the MgO layer on the alloys without Be. Hence, it is considered that during high temperature oxidation, the accumulation of Be on the surface of Mg alloys reinforced the initially XI My special thanks also go to Prof. Fusheng Pan for his insightful advices on my projec...

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Effect of Ce addition on the high‐temperature oxidation resistance of Mg–Gd alloys

Jiang

et al. 2022

Materials & Corrosion

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In the present study, the oxidation resistance of magnesium alloyed with Gd and Ce was investigated. The high-temperature oxidation resistance of Mg-3.5Gd-xCe (x = 0, 0.2, 0.4, 0.7 and 1.0 wt%) alloys was evaluated at temperatures between 550°C and 650°C. Results indicate that adding less than 0.7 wt% Ce resulted in high oxidation resistance, whereas the Ce addition exceeding 0.7 wt% deteriorated the oxidation resistance. The high oxidation resistance phenomenon is attributed to the formation of compact oxide films primarily composed of MgO, Gd 2 O 3 , and a small amount of CeO 2 on the surface of Mg-3.5Gd-0.2Ce and Mg-3.5Gd-0.4Ce alloys. These compact oxide films can prevent the matrix from experiencing further oxidation. The deteriorated oxidation resistances of Mg-3.5Gd-0.7Ce and Mg-3.5Gd-1Ce alloys were found to be due to the severe internal oxidation caused by the distributed Mg 12 Ce phases along the grain boundaries.

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Oxidation resistance of Mg–9Al–1Zn alloys micro-alloyed with Be

Cited by 46 publications

References 21 publications

Oxidation of magnesium alloys at elevated temperatures in air: A review

Oxidation of magnesium alloys at elevated temperatures in air: A review

Influence of trace addition of Be on the oxidation behaviour of Mg alloys

Effect of Ce addition on the high‐temperature oxidation resistance of Mg–Gd alloys

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