Quantitative Study of Microstructure-Dependent Thermal Conductivity in Mg-4Ce- x Al-0.5Mn Alloys
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WITH the increasing power density of integrated circuits, heat sinks in modern electronic devices must possess high heat-dissipation capability to remove excess heat from the devices. The other important requirement for a high-quality heat spreader is light weight, which is important for laptops, mobile phones, and other communication devices.[1] Owing to the low density, high specific strength, reasonable thermal conductivity, and excellent electromagnetic shielding, magnesium alloys have been considered as potential heat-dissipation
CHUANGYE SU is 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 and also with the Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210. DEJIANG LI is with the National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University. Contact email: [email protected] ALAN A. LUO and RENHAI SHI are with the Department of Materials Science and Engineering, The Ohio State University. 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 The State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China. Contact email: [email protected] Manuscript submitted September 18, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS A
materials.[2] Due to its high productivity for the manufacture of complex, thin-walled and near-net-shaped parts, high-pressure die casting (HPDC) is a dominant processing method to produce heat sinks of magnesium alloys.[3] Many widely used HPDC Mg alloys are based on the Mg-Al system, which possesses both good mechanical property at ambient temperature and outstanding castability at elevated temperature. However, these alloys exhibit low thermal conductivity. For example, the thermal conductivity values of AM60 and AZ91 are only 63 W/(m K)[4] and 53 W/(m K),[5] respectively. Therefore, it is necessary to develop a die casting Mg alloy with a high thermal conductivity. In contrast to the tremendous work done on mechanical property, the information about the thermal conductivity of Mg alloys was relatively scarce, especially for die casting Mg alloys. Rudajevova´ et al.[4] demonstrated that the thermal conductivity values of AM20, AM50, and AM60 alloys were sensitive to their microstructures. The alloys with Al element dissolved in the Mg matrix had lower thermal conductivity than the alloys where Mg17Al12 phase was present. Wang et al.[6] showed that the thermal conductivity in aged Mg-5Sn alloy increased with the increasing aging time, which was mainly due to the gradual decrease of Sn solute atoms in the Mg matrix. These suggest that Mg alloys with high thermal conductivity could be designed by alloying metal elements with low
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