Simultaneous Improvement of Thermal Conductivity and Strength for Commercial A356 Alloy Using Strontium Modification Process

다국어 초록 (Multilingual Abstract)

The Aluminum–Silicon (Al–Si) die-casting alloys, such as the commercial A356 alloy, are expected to be used in heat-sinkand the device with high thermal conductivity due to their high production efficiency of casting process. These fields alsorequired them to possess sound mechanical properties. To meet these demands, the Strontium (Sr) was often utilized tomodify the silicon phase. According to our current work, the secondary dendrite arm spacing of the α-Al grains prominentlywas decreased when 0.05%–0.25% strontium was added. The decrease of the secondary dendrite arm spacing (SDAS) lead tothe enhancement of the mechanical strength as well as the improvement of the thermal and electrical conductivity. When theSr dosage was 0.15% in the commercial A356 alloy, the strength and the thermal conductivity of the A356 alloy simultaneouslyreached the maximum value. The improvement of the electrical and thermal conductivity might by contributed by theformation of a good conductor, Al2Si2Srphase, on the Si surface. Further investigations suggested that the improvement ofthermal conductivity was mainly due to the modification effect of Sr on the eutectic Si phase, which enlarged the specificarea between the α-Al/eutectic Si interface. The WDS analysis indicated that the solubility of Si decreased in aluminummatrix by increasing in the Sr dosage. However, the excessive dosage of strontium would result in the coarsening of themodified silicon phase, deteriorating the strength and the thermal and electrical conductivity of the modified A356 alloys.

참고문헌 (Reference)

1 "https://www.materialsproject.org/"

2 J. Manickaraj, "X-ray nano-difraction study of Sr intermetallic phase during solidifcation of Al–Si hypoeutectic alloy" 104 : 145-, 2014

3 R. N. Lumley, "Thermal characteristics of heat-treated aluminum high-pressure die-castings" 58 : 1006-1009, 2008

4 J. K. Chen, "Thermal and electrical conductivity in Al–Si/Cu/Fe/Mg binary and ternary Al alloys" 50 : 5630-5639, 2015

5 M. Malekan, "Thermal analysis study on the simultaneous grain refnement and modifcation of 380.3aluminum alloy" 115 : 393-399, 2014

6 K. Wang, "Thermal analysis of in-situ Al2O3/SiO2(p)/Al composites fabricated by stir casting process" 641 : 29-38, 2016

7 Z. Yang, "The infuence of silicon content on the thermal conductivity of Al–Si/diamond composites" 2009

8 X. Cui, "The improvement of electrical conductivity of hypoeutectic Al–Si alloys achieved by composite melt treatment" 788 : 1322-1328, 2019

9 M. H. Mulazimoglu, "The electrical conductivity of cast Al−Si alloys in the range 2 to 12.6 wt pct silicon" 20 : 383-389, 1989

10 Y. Wang, "The effects of eutectic silicon on grain refnement in an Al–Si alloy processed by accumulative continuous extrusion forming" 52 : 1137-1148, 2017

11 M. Emamy, "The effect of sr and grain refning elements on the microstructure and tensile properties of A356–10%B4C metal matrix composite" 18 : 210-217, 2011

12 F. Stadler, "The effect of main alloying elements on the physical properties of Al–Si foundry alloys" 560 : 481-491, 2013

13 H. Yamagata, "The effect of average cooling rates on the microstructure of the Al–20% Si high pressure die casting alloy used for monolithic cylinder blocks" 203 : 333-341, 2008

14 N. D. Alexopoulos, "The effect of Cu, Ag, Sm and Sr additions on the statistical distributions of Si particles and tensile properties in A357–T6alloy castings" 604 : 40-45, 2014

15 Y. M. Kim, "The behavior of thermal diffusivity change according to the heat treatment in Al–Si binary system" 687 : 54-58, 2016

16 G. V. Voort, "The Al–Si phase diagram" 15 : 60-61, 2009

17 R. Landauer, "Solid state physics" 160 : 736-741, 2006

18 S. Miresmaeili, "Precipitation of Sr-rich intermetallic particles and their infuence on pore formation in Sr-modifed A356 alloy" 36 : 2341-2349, 2005

19 P. Rao, "On the modifcation and segregation behavior of Sb in Al–7Si alloy during solidifcation" 62 : 2013-2016, 2008

20 A. M. Samuel, "New method of eutectic silicon modifcation in cast Al–Si alloys" 11 : 475-493, 2017

21 H. Qiu, "Modifcation of near-eutectic Al–Si alloys with rare earth element samarium" 29 : 1270-1277, 2014

22 A. Knuutinen, "Modifcation of Al–Si alloys with Ba, Ca, Y and Yb" 1 : 229-240, 2001

23 A. Mazahery, "Modifcation mechanism and microstructural characteristics of eutectic Si in casting Al–Si alloys : a review on experimental and numerical studies" 66 : 726-738, 2014

24 Z. Cong, "Microstructure and thermal conductivity of the as-cast and annealed Al–Cu–Mg–Si alloys in the temperature range from 25 °C to 400°C)" 36 : 2869-2880, 2015

25 Y. Zhang, "Mechanical properties and damping capacity after grain refnement in A356 alloy" 59 : 2174-2177, 2005

26 M. C. S. Jr, "Machining of aluminum alloys : a review" 86 : 1-14, 2016

27 J. Barcena, "Innovative packaging solution for power and thermal management of widebandgap semiconductor devices in space applications" 62 : 422-430, 2008

28 S. G. Shabestari, "Infuence of modifcation, solidifcation conditions and heat treatment on the microstructure and mechanical properties of A356 aluminum alloy" 39 : 2023-2032, 2004

29 W. Prukkanon, "Infuence of Sc modifcation on the fuidity of an A356 aluminum alloy" 487 : 453-457, 2009

30 J. Eiken, "Impact of P and Sr on solidifcation sequence and morphology of hypoeutectic Al–Si alloys : combined thermodynamic computation and phase-feld simulation" 98 : 152-163, 2015

31 F. Stadler, "ICAA13 Pittsburgh" Springer International Publishing 137-142, 2016

32 W. Kurz, "Fundamentals of Solidifcation" Trans Tech Publications Ltd 1998

33 A. M. Garay-Tapia, "Firstprinciples investigation of the Al–Si–Sr ternary system : ground state determination and mechanical properties" 21 : 31-44, 2012

34 S. Shabestari, "Effects of Sr-modifcation and melt cleanliness on melt hydrogen absorption of 319 aluminium alloy" 38 : 1901-1907, 2003

35 S. W. Choi, "Effect of the precipitation of secondary phases on the thermal difusivity and thermal conductivity of Al–4.5Cu alloy" 688 : 897-902, 2016

36 C. Su, "Effect of solute atoms and second phases on the thermal conductivity of Mg-RE alloys : a quantitative study" 747 : 431-437, 2018

37 A. M. Samuel, "Effect of grain refning and Sr-modifcation interactions on the impact toughness of Al–Si–Mg cast alloys" 56 : 264-273, 2014

38 Z. Zhang, "Effect of Sr-modifying T reatment on hydrogen absorption of the melt and the shape of porosities" 1 : 5-8, 1999

39 P. Olafsson, "Comparison of experimental, calculated and observed values for electrical and thermal conductivity of aluminium alloys" 32 : 4383-4390, 1997

40 J. Barrirero, "Cluster formation at the Si/liquid interface in Sr and Na modifed Al–Si alloys" 117 : 16-19, 2016

41 K. Wang, "Characterization of microstructures and tensile properties of recycled Al–Si–Cu–Fe–Mn alloys with individual and combined addition of titanium and cerium" 2018 : 1-14, 2018

42 R. Herman, "An introduction to electrical resistivity in geophysics" 69 : 943-, 2001

43 W.M. Doyle, "Aluminum alloys: structure and properties" 1976

44 W. Lu, "A study on the fading of Sr-modifed Al–Si alloy" 1 : 1-5, 1995

45 S. Farahany, "A new approach to assess the effects of Sr and Bi interaction in ADC12Al–Si die casting alloy" 575 : 179-187, 2014