Morphologically templated nucleation of primary Si on AlP in hypereutectic Al-Si alloys

2021 ◽  
Author(s):  
Xiangzhen Zhu ◽  
Shihao Wang ◽  
Xixi Dong ◽  
Xiangfa Liu ◽  
Shouxun Ji
Keyword(s):  
Primary Si

scholarly journals Nucleation Behavior of a Single Al-20Si Particle Rapidly Solidified in a Fast Scanning Calorimeter

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2920
Author(s):  
Qin Peng ◽  
Bin Yang ◽  
Benjamin Milkereit ◽  
Dongmei Liu ◽  
Armin Springer ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Rapid Solidification ◽  
Heterogeneous Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Solidification Behavior ◽  
Nucleation Kinetics ◽  
Nucleation Behavior ◽  
Nucleation Undercooling ◽  
Primary Si

Understanding the rapid solidification behavior characteristics, nucleation undercooling, and nucleation mechanism is important for modifying the microstructures and properties of metal alloys. In order to investigate the rapid solidification behavior in-situ, accurate measurements of nucleation undercooling and cooling rate are required in most rapid solidification processes, e.g., in additive manufacturing (AM). In this study, differential fast scanning calorimetry (DFSC) was applied to investigate the nucleation kinetics in a single micro-sized Al-20Si (mass%) particle under a controlled cooling rate of 5000 K/s. The nucleation rates of primary Si and secondary α-Al phases were calculated by a statistical analysis of 300 identical melting/solidification experiments. Applying a model based on the classical nucleation theory (CNT) together with available thermodynamic data, two different heterogeneous nucleation mechanisms of primary Si and secondary α-Al were proposed, i.e., surface heterogeneous nucleation for primary Si and interface heterogenous nucleation for secondary α-Al. The present study introduces a practical method for a detailed investigation of rapid solidification behavior of metal particles to distinguish surface and interface nucleation.

A High Effective and Low-Cost Modifier for Hypereutectic Al-Si Alloys

2013 ◽  
Vol 721 ◽  
pp. 282-286
Author(s):  
Guang Hui Qi
Keyword(s):  
Grain Size ◽  
Master Alloy ◽  
Low Cost ◽  
Environment Pollution ◽  
Casting Method ◽  
Good Future ◽  
Primary Si ◽  
Average Grain Size ◽  
Master Alloys

In order to settle environment pollution and provide a high effective and low-cost modifier for refining the primary Si in hypereutectic Al-Si alloys, Al-Fe-P master alloys containing 2.0~5.0% phosphorus have been invented by casting method. The Al-Fe-P master alloys can be conveniently produced and an excellent modification can be obtained by adding 0.3~0.8wt% Al-Fe-P master alloy in Al-Si alloys containing 12%-25% Si at a relatively lower modifying temperature. The number of primary Si increases obviously and the average grain size of primary Si decreases largely, less than 50μm. Furthermore Al-Fe-P master alloys have many advantages, such as low cost, convenient operation technology, no pollution, stable and long-term modification effect, easy storage and etc. Al-Fe-P master alloys have overcome the shortages of current modifier and have a good future for hypereutectic Al-Si alloy modification.

Porosity Development and Modification in Al-Si Alloys: Effect of P and Sr

2019 ◽  
Author(s):  
J. Campbell ◽  
Murat Tiryakioğlu
Keyword(s):  
Mechanical Properties ◽  
Liquid Metal ◽  
Crack Size ◽  
Primary Si ◽  
Interdendritic Flow ◽  
Oxide Bifilms ◽  
Lower Temperature ◽  
Porosity Development ◽  
Silicon Particles ◽  
Crystalline Growth

The benefits of Sr additions to Al–Si alloys to modify the eutectic are often impaired by the development of porosity, sometimes to the degree that benefits are negated. Experimental reports are reviewed in this paper, suggesting an explanation in terms of the oxide population in the melt. The unmodified silicon particles are nucleated by AlP, which has in turn nucleated on oxide bifilms. The oxide bifilms, which are essentially cracks, are straightened by the crystalline growth of Si particles, leading to increased crack size and consequently reduced mechanical properties. The addition of Sr improves properties by suppressing the formation of Si on bifilms and thereby preventing the straightening of the pre-existing cracks. Si is now forced to precipitate at a lower temperature as a coral-like eutectic. Unfortunately, the bifilms are now freed (the primary Si particles no longer exist to grow around and sequester the bifilms), remaining in suspension in the liquid metal, allowing them to act to block interdendritic flow and aid the initiation of the formation of pores, countering the benefits of the improved structure.

scholarly journals Enhancement of the Mechanical Properties in Al–Si–Cu–Fe–Mg Alloys with Various Processing Parameters

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2150 ◽  
Author(s):  
Su-Seong Ahn ◽  
Sharief Pathan ◽  
Jar-Myung Koo ◽  
Chang-Hyun Baeg ◽  
Chan-Uk Jeong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Silicon Content ◽  
Compositional Analysis ◽  
Processing Parameters ◽  
Silicon Phase ◽  
X Ray ◽  
Primary Si ◽  
Transmission Electron ◽  
Eutectic Si

In this research, various processing conditions were implemented to enhance the mechanical properties of Al-Si alloys. The silicon content was varied from hypoeutectic (Si-10 wt.%) to eutectic (Si-12.6 wt.%) and hypereutectic (Si-14 wt.%) for the preparation of Al-XSi-3Cu-0.5Fe-0.6 Mg (X = 10–14%) alloys using die casting. Subsequently, these alloys were hot-extruded with an optimum extrusion ratio (17:1) at 400 °C to match the output extruded bar to the compressor size. An analysis of the microstructural features along with a chemical compositional analysis were carried out using scanning electron microscope along with energy dispersive X-ray spectroscopy and transmission electron microscope. The SEM micrographs of the extruded samples displayed cracks in primary Si, and the intermetallic (β-Al5FeSi) phase was fragmented accordingly. In addition, the silicon phase was homogenously distributed, and the size remained constant. The mechanical properties of the extruded samples were enhanced by the increase of silicon content, and consequently the ductility decreased. By implementing proper T6 heat treatment parameters, coherent Al2Cu phases were formed in the Al matrix, and the Si phase was gradually increased along with the silicon content. Therefore, high tensile strength was achieved, reaching values for the Al-XSi-3Cu-0.5Fe-0.6Mg (X = 10–14%) alloys of 366 MPa, 388 MPa, and 420 MPa, respectively.

scholarly journals Investigation on Microstructures and Mechanical Properties of the Hypoeutectic Al-10Si-0.8Fe-XEr Alloy

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Peng Tang ◽  
Yiyuan Liu ◽  
Yanjun Zhao ◽  
Zhiliu Hu ◽  
Huachun Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Secondary Phase ◽  
Metallographic Analysis ◽  
Analysis Techniques ◽  
Microstructure Modification ◽  
Primary Si ◽  
Eutectic Si ◽  
Second Phases ◽  
The Mean

In this paper, the effect of Er addition (0.2, 0.5, 0.65, 0.8, 1.0, and 1.5 wt. %) on the microstructure evolution and tensile properties of as-cast hypereutectic Al-10Si-0.8Fe alloy was investigated. The phases and their morphologies in these alloys were identified by XRD and SEM equipped with EDX with the help of metallographic analysis techniques; the length of the secondary phase (LSP) and secondary dendrite arm spacing (SDAS) of α-Al grain were quantified. The results indicated that the second phases (primary Si, eutectic Si, and iron-rich phases) and α-Al grain were significantly refined when the addition of Er increased from 0 to 0.8 wt. %. The mean LSP and SADS values were decreased to a minimum value when the Er addition reached 0.8 wt. %. However, the second phases and α-Al grain became coarser when the level of Er increased more than 0.8 wt. %. The analysis of XRD shows that Er mainly exists in the form of Er2Si compound. The microstructure modification also has a significant effect on the mechanical properties of the alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) increase from 52.86 MPa, 163.84 MPa, and 3.45% to 71.01 MPa, 163.84 MPa, and 5.65%, respectively. From the fracture surface, the promotions of mechanical properties are due to the dispersion and pinning reinforcement caused by the Er2Si phase.

scholarly journals A novel Zn-Cu-P master alloy and its modification performance on primary Si of A390 alloy

2019 ◽  
Vol 12 ◽  
pp. 1006-1010 ◽  
Author(s):  
Tong Gao ◽  
Yihan Bian ◽  
Xiangfa Liu
Keyword(s):  
Master Alloy ◽  
Primary Si ◽  
A390 Alloy

High-Current Pulsed Electron Treatment of Hypoeutectic Al–10Si Alloy

2017 ◽  
Vol 36 (1) ◽  
pp. 97-100 ◽  
Author(s):  
Lu Diankun ◽  
Gao Bo ◽  
Zhu Guanglin ◽  
Lv Jike ◽  
Hu Liang
Keyword(s):  
Wear Resistance ◽  
Surface Layer ◽  
Beam Energy ◽  
High Current ◽  
Pulsed Electron Beam ◽  
Surface Nanocrystallization ◽  
Primary Si ◽  
Beam Energy Density ◽  
Eutectic Si ◽  
First Time

AbstractThis paper reports, for the first time, an analysis of the effect of high-current pulsed electron beam (HCPEB) on a hypoeutectic Al–10Si alloy. The Al–10Si alloy was treated by HCPEB in order to see the potential of this fairly recent technique in modifying its wear resistance. For the beam energy density of 3 J/cm2 used in the present work, the melting mode was operative and led to the formation of a “wavy” surface and the absence of mass primary Si phase and eutectic microstructure. The surface nanocrystallization of primary and eutectic Si phases led to the increase in macro-hardness of the top surface layer, and the wear resistance was drastically improved with a factor of 4.

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