Formation and thermal stability of connected hard skeleton structure in ATX525 cast alloys

• Main Authors: Ke-qiang Qiu, Hui-han Zhang, Yan Re
• Format: Article
• Language: English
• Published: Foundry Journal Agency 2015-11-01
• Series: China Foundry
• Subjects: Mg cast alloy; connected hard skeleton structure; isothermal treatment; thermal stability; heat resistance
• Online Access: http://ff.foundryworld.com/uploadfile/2015121550290029.pdf

The formation and the thermal stability of a connected hard skeleton structure (CHSS) in the matrix of Mg-5Al-2Sn-5Ca (ATX525) alloy were investigated by using X-ray diffractometer, scanning electron microscopy, differential scanning calorimeter, creep tester and isothermal treatment method. The results indicated that the CHSS composed of Mg2(Al,Ca) and Al2Ca intermetallics was formed into a typical eutectic structure and no obvious change occurred when the samples were isothermally treated at 250 °C for 96 h and 350 °C for 72 h, respectively. It became a chained structure when isothermally treated at 450 °C for 48 h. The dissolution and reconstruction processes, however, were observed for the CHSS when the processing temperature was up to 550 °C. The creep life at the stress-temperature condition of 50MPa/200°C for the alloy treated at 450 °C for 48 h was as high as 510 h, and the strain at creep time of 100 h was as low as 0.03%, which indicated that the present alloy has not only a good thermal stability, but also a better heat resistance.