Microstructure evolution, thermal conductivity and mechanical properties of hot-rolling Al–Si–Fe–Mg alloy under different reductions

2021 ◽  
Author(s):  
Yu Guo ◽  
Ye Wang ◽  
Bo Jiang ◽  
Hongtao Chen ◽  
Hongyu Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Hot Rolling ◽  
Eutectic Silicon ◽  
Mg Alloy ◽  
Free Electrons ◽  
Silicon Phase ◽  
Transport Channel ◽  
Overall Performance ◽  
Average Size

To further improve the properties of the Al–11.5Si–0.4Fe–0.35Mg, the effects of different reductions of hot-rolling (HR) Al–Si–Fe–Mg alloy on microstructure, thermal conductivity (TC), and mechanical properties were investigated in this paper. The results show that the eutectic silicon phases are broken and moved during the HR process. The average size of eutectic silicon phase decreases. Meanwhile, the aspect ratio of eutectic silicon phase closer to 1 and the distribution of that are more uniform with the increase of HR reduction. In addition, the ternary Al–Fe–Si phases are also broken after HR. It indicates that the action of shear force induced by the HR process is beneficial to promote refinement and spheroidization of the eutectic silicon phase, hence further improves the properties of the alloy. Apparently, the fine and dispersed distribution of spherical silicon particles can minimize the splitting of the [Formula: see text]-Al matrix, decrease the scattering effect on free electrons, and increase the number of free-electron transport channel. Therefore, the overall performance of HR Al–Si–Fe–Mg alloy with a reduction of 71.25% is the best with the TC of 170.24 W/m[Formula: see text]K, the tensile strength of 241.98 MPa and elongation of 8.73%, respectively.

scholarly journals Microstructures and Mechanical Properties of Al-2Fe-xCo Ternary Alloys with High Thermal Conductivity

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3728
Author(s):  
Gan Luo ◽  
Yujian Huang ◽  
Chengbo Li ◽  
Zhenghua Huang ◽  
Jun Du
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Fine Particles ◽  
Ternary Alloys ◽  
Thermal And Mechanical Properties ◽  
Free Electrons ◽  
Unmodified Alloy ◽  
Cast Alloys

The microstructures, mechanical properties, and thermal conductivity (TC) of Al-2Fe-xCo (x = 0~0.8) alloys in as-cast, homogeneous annealed, and cool rolled states are systematically studied. Results indicate that appropriate Co modification (x ≤ 0.5) simultaneously improves the thermal and mechanical properties of as-cast Al-2Fe alloys. The improvement of TC is attributed to ameliorating the morphology of primary Al3Fe phases from needles to short rods and fine particles, which decreases the scattering probability of free electrons during the electronic transmission. However, further increasing the Co content (x = 0.8) decreases the TC due to the formation of a coarse plate-like Al2FeCo phase. Besides, the thermal conductivity of annealed Al-2Fe-xCo alloys is higher than that of as-cast alloys because of the elimination of lattice defects and spheroidization of Al3Fe phases. After cool rolling with 80 % deformation, thermal conductivity of alloys slightly increases due to the breaking down of Al2FeCo phases. The rolled Al-2Fe-0.3Co alloy exhibits the highest thermal conductivity, which is about 225 W/(m·K), approximately 11 % higher than the as-cast Al-2Fe sample. The ultimate tensile strength (UTS) and elongation (EL) of as-cast Al-2Fe-0.5Co (UTS: 138 MPa; EL: 22.0 %) are increased by 35 % and 69 %, respectively, compared with those of unmodified alloy (UTS: 102 MPa; EL: 13.0 %).

scholarly journals Effect of Short T6 Heat Treatment on the Thermal Conductivity and Mechanical Properties of Different Casting Processes Al-Si-Mg-Cu Alloys

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1450
Author(s):  
Zhong-Qiang Dong ◽  
Jin-Guo Wang ◽  
Zhi-Ping Guan ◽  
Pin-Kui Ma ◽  
Po Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Heat Treatment ◽  
Eutectic Silicon ◽  
Cast State ◽  
Relevant Research ◽  
T6 Heat Treatment ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Semi Solid

The thermal conductivity of alloys is gradually becoming appreciated. It is often assumed that heat treatment can improve the thermal conductivity of Al-Si-Mg-Cu alloys, but there has been little relevant research. This paper studies the effects of different casting processes and short T6 heat treatment (ST6) on the thermal conductivity and mechanical properties of Al-Si-Mg-Cu alloys. The results show that a microstructure with fine α-Al crystal grains can be obtained by semi-solid die casting (SSDC), improving the mechanical properties of the Al-Si-Mg-Cu alloy in the as-cast state. After SSDC, the size and aspect ratio of eutectic silicon can be reduced by ST6 treatment, effectively improving the thermal conductivity and mechanical properties of the alloy. Finally, the influence of eutectic silicon on electron transport is analyzed in detail. With the SSDC + ST6 processing technology, Al-Si-Mg-Cu alloys with excellent thermal conductivity and mechanical properties can be obtained.

scholarly journals Graphene platelets enhanced pressureless- sintered B 4 C ceramics

2018 ◽  
Vol 5 (4) ◽  
pp. 171837 ◽  
Author(s):  
Dezhi Gao ◽  
Jie Jing ◽  
Jincheng Yu ◽  
Xue Guo ◽  
Yubai Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Electrical Resistivity ◽  
Optimal Condition ◽  
Bending Strength ◽  
Extreme Values ◽  
Overall Performance ◽  
Graphene Platelets

B 4 C ceramics with different contents of graphene platelets (GPL) were synthesized by a pressureless process in Ar atmosphere. The influences of GPL on mechanical properties, thermal conductivity and electrical resistivity of the B 4 C ceramics were investigated. Mechanical properties ran up to optimal condition with hardness of 29.1 GPa, bending strength of 383.9 GPa and fracture toughness of 5.72 MPa m 1/2 with 0.8 wt% GPL separately. Thermal conductivity and electrical resistivity reached extreme values of 26.35 W m −1  k −1 and 0.1 Ω cm −1 . Performances of the ceramics were mainly affected by the generation of non-functional-GPL and the result indicated that a large amount of non-functional-GPL could contribute to poorer overall performance. Meanwhile, two particular pullout mechanisms concerning toughness enhancing was discussed in detail.

Development of high mechanical properties and moderate thermal conductivity cast Mg alloy with multiple RE via heat treatment

2018 ◽  
Vol 34 (7) ◽  
pp. 1076-1084 ◽  
Author(s):  
Guoqiang Li ◽  
Jinghuai Zhang ◽  
Ruizhi Wu ◽  
Yan Feng ◽  
Shujuan Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Heat Treatment ◽  
Mg Alloy

scholarly journals Research on Microstructure and Growth Mechanism of Different Primary Silicon in Hypereutectic Aluminum Alloy

2022 ◽  
Vol 2152 (1) ◽  
pp. 012022
Author(s):  
Gaozhan Zhao ◽  
Zhihui Xing ◽  
Ming Li ◽  
Shiqing Gao ◽  
Jianquan Tao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Growth Mechanism ◽  
Eutectic Silicon ◽  
Primary Silicon ◽  
Phase Growth ◽  
Silicon Phase ◽  
Tetrahedral Crystal ◽  
Impurity Elements ◽  
Growth Methods ◽  
Cast Microstructure

Abstract The as-cast microstructure of a typical hypereutectic Al-25Si alloy was studied, and the growth mechanism of different primary silicon phases was analyzed. The results show that the as-cast microstructure phase composition of the alloy is mainly primary silicon and eutectic silicon. Primary silicon is mainly petal-like, massive and other complex polyhedrons, and there are a lot of cavities, cracks and other defects in the interior and boundary; Eutectic silicon is coarse and long needle-like, and the distribution is relatively messy, which seriously deteriorates the mechanical properties and cutting performance, and hinders the further application of the alloy in the field of lightweight pistons. Petal-shaped primary silicon is grown by combining five tetrahedral crystal nuclei in the melt into a decahedron, while bulk primary silicon is mainly caused by the unbalanced aggregation of impurity elements. And these two types of silicon phase growth methods are related to the twin groove growth mechanism, which is the result of a combination of multiple mechanisms.

Modification of Hypereutectic Al-20%Si Alloy by Neodymium

2015 ◽  
Vol 1095 ◽  
pp. 180-183
Author(s):  
Wei Xi Shi ◽  
Cheng Wu Du ◽  
Guang Zhe Lv ◽  
Chang Wan Liu
Keyword(s):  
Mechanical Properties ◽  
Trace Element ◽  
Base Metal ◽  
Eutectic Silicon ◽  
Trace Element Analysis ◽  
Primary Silicon ◽  
Sem Analysis ◽  
Silicon Phase ◽  
Element Analysis ◽  
Average Grain Size

The modification mechanism was studied by OM, SEM, XRD and Trace Element Analysis. The results of OM and SEM analysis show that pure Nd can effectively refine primary and eutectic silicon in hypereutectic Al-20%Si alloy. Morphology of primary silicon is transformed from pentalpha to block and the average grain size of primary silicon is reduced from 80~120μm to 20~50μm after modification. Trace Element Analysis results show that Nd can purity base metal and reduce impurity contents. XRD patterns show that no new phase formed after Nd modification. The results of mechanical properties test show that whole properties of modified sample are significantly improved. Tensile strength increases about 35.8% from 117 MPa to 148 MPa after modification, Elongation change increases about 193% from 0.56% to 1.64%. The improvement of mechanical properties should be attributed to fine primary Si phase and eutectic silicon phase and purification of base metal after modification.

An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

2015 ◽  
Vol 10 (2) ◽  
pp. 2663-2681
Author(s):  
Rizk El- Sayed ◽  
Mustafa Kamal ◽  
Abu-Bakr El-Bediwi ◽  
Qutaiba Rasheed Solaiman
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Melt Spinning ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
Microstructural Analysis ◽  
Alloy System ◽  
Antimony Content ◽  
The Stability ◽  
Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as melt–spun ribbons  as a function of antimony content .The stability  of these structures has  been  related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition.  The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes. 

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