Hot Tearing Behavior in Double Ternary Eutectic Alloy System: Mg-Ce-Al Alloys
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the lightest metal structural materials, magnesium alloys have high specific strength, good damping capability, and easy recyclability, in addition to low density.[1,2] However, most commercial magnesium alloys, such as magnesium-aluminum-based alloys (Mg-Albased alloys), are limited to room temperature applications due to their poor creep resistance at elevated temperatures.[3,4] Magnesium-cerium-aluminum alloys, such as Mg-4Ce-xAl (x = 0 to 9 wt pct) alloys, which belong to double ternary eutectic alloy system (there are two ternary eutectic reaction platforms in this alloy system with the change of Al content), have good creep resistance and mechanical properties, owing to the formation of more stable and finer Al11Ce3 instead of
BO HU, DEJIANG LI, JINGYA WANG, ZIXIN LI and XUEYANG WANG are with the National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China. Contact e-mail: [email protected] XIAOQIN ZENG is with the National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University and also with The State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China. Contact e-mail: [email protected] Manuscript submitted August 13, 2020; accepted September 24, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS A
phase.[5–7] Besides, the networked Mg17Al12 Mg-4Ce-xAl alloys have excellent thermal conductivity, which makes them have extensive application prospects in the computer, communication and consumer electronic fields.[7] However, their die-cast production is limited by hot tearing, so it is necessary to investigate how the Ce/Al ratio adjust the HTS of Mg-4Ce-xAl alloys. Hot tearing occurs above the solidus temperature[8,9] due to the lack of feeding when stress or strain exceeds the strength or ductility of casting at elevated temperature.[10] The stress and strain generally arise from restriction of solidification shrinkage and thermal contraction. In addition, the stress and strain are concentrated at the hot spots where the casting solidifies last or at areas with sudden changes of cross section.[11–13] Therefore, hot tearing is prone to occur at the hot spot. Rosenberg’s[14] work helped to establish the effect of alloy composition on hot tearing. For most binary alloys, the relationship between HTS and alloy composition can be characterized by the so-called k-curve, which describes that the HTS increases first then decreases with the increasing of alloying element content. Researchers[15–17] reported that the HTS of binary Mg-Ce and Mg-Al alloys followed the k-curve and the peak points appeared between 0.53 to 0.94 wt pct Ce and at 1 wt pct Al, respectively. However, up to now, there is still no specific curve to describe the HTS of ternary magnesium alloys, and rare research has reported the relationship of HTS between binary and
ternary alloys, especiall
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