The Influence of Calcium on the Primary Mg2Si Phase in the Hypereutectic Mg-Si Alloys

2015 ◽  
Vol 229 ◽  
pp. 71-76 ◽  
Author(s):  
Tomasz Rzychoń ◽  
Radosław Janik
Keyword(s):  
Solid Solution ◽  
Chinese Script ◽  
Coarse Dendrite ◽  
Modification Effect ◽  
Polyhedral Shape ◽  
Primary Crystals

The microstructure of Mg-5Si alloy consists of the primary coarse Mg2Si phase, α-Mg solid solution and eutectic α-Mg + Mg2Si, in which eutectic Mg2Si phase solidifies in the form of Chinese script particles. When 0.2 wt.% of Ca was added to the Mg-5Si alloy the size of primary Mg2Si phase remained unchanged. The modification effect of calcium on the primary Mg2Si phase was effective only in the Mg-5Si-0.5Ca alloy. The morphology of the primary Mg2Si phase is changed from the coarse dendrite shape to polyhedral shape and the size of primary crystals is significantly reduced. The addition of 0.6 wt.% Ca to Mg-7Si alloy did not cause the modification of primary Mg2Si phase.

Effects of Melt Holding Time on as Cast Microstructure and Tensile Properties of Sr-Modified AS31Alloy

2014 ◽  
Vol 697 ◽  
pp. 67-71 ◽  
Author(s):  
Jin Wei Wang ◽  
Ji Xue Zhou ◽  
Bai Chang Ma ◽  
Shou Qiu Tang ◽  
Fu Min Chu ◽  
...  
Keyword(s):  
Grain Size ◽  
Elevated Temperature ◽  
Ambient Temperature ◽  
Tensile Properties ◽  
Holding Time ◽  
Chinese Script ◽  
Modification Effect ◽  
Average Grain Size ◽  
Polyhedral Shape ◽  
Cast Microstructure

Melt holding time has important influences on the modification effect of Sr modified AS31 alloy. Effects of different melt holding time (30min, 60min, 90min and 120min) at 700°C on as cast microstructure and tensile properties both at ambient temperature and elevated temperature of Sr-modified AS31 alloy were studied. There exist polyhedral shape, fine fibers shape and a few Chinese script Mg2Si particles in Sr-modified AS31 alloys. And the average grain size is smallest in Sr-modified AS31 alloys with holding time at 700°C for 30min. The ultimate strength, yield strength and elongation at both ambient temperature and 150°C decrease gradually when the melt holding time increases from 30min to 120min. In the process of smelting of Sr-modified AS31. The burning loss of Sr element becomes more serious with the prolongation of melt holding time, which contributes to the modification effect reducing.

Microstructure of Hypereutectic Mg-Si Alloy with Sn, Al and Mn Additions

2015 ◽  
Vol 229 ◽  
pp. 65-70 ◽  
Author(s):  
Tomasz Rzychoń
Keyword(s):  
Solid Solution ◽  
Chinese Script ◽  
Mn Additions

In the present study, the microstructure of Mg-5Si alloys with tin, aluminum and manganese was investigated. The microstructure of Mg-5Si alloy consists of the primary coarse Mg2Si phase, α-Mg solid solution and eutectic α-Mg + Mg2Si in which the eutectic Mg2Si phase solidifies in the form of Chinese script particles. The Mg2Sn phase and α-Mg solid solution with tin appear in the microstructure, when 7 wt.% of Sn was added to the Mg-5Si alloy. Aluminum dissolve in the α-Mg matrix and participates in the formation of Al2Sn phase. The addition of manganese promotes the formation of Mn5Si3 compound.

Effects of Different Sr Additions on As Cast Microstructure and Tensile Properties of AS31 Alloy

2014 ◽  
Vol 788 ◽  
pp. 110-114 ◽  
Author(s):  
Ji Xue Zhou ◽  
Dong Qing Zhao ◽  
Jin Wei Wang ◽  
Shou Qiu Tang ◽  
Wei Hong Li
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Elevated Temperature ◽  
Magnesium Alloy ◽  
Ambient Temperature ◽  
Tensile Properties ◽  
Mass Fraction ◽  
Chinese Script ◽  
Polyhedral Shape ◽  
Cast Microstructure

Effects of different Sr additions (0.1%-1%Sr, mass fraction) on as-cast microstructure and tensile properties both at ambient temperature and elevated temperature of AS31 magnesium alloy were studied. The experimental results show that the addition of Sr could refine the grain size obviously and modify the eutectic Mg2Si from Chinese script shape to polyhedral shape or fine fibers shape. The addition of Sr to AS31 alloy improved the tensile strength at ambient temperature, and the ultimate strength at 150°C first decrease and then increase with the Sr addition increase from 0.1% to 1%Sr.

Effects of Sb and RE on the Solutionized Microstructure and Microhardness of Mg-6A1-1Zn-0.7Si Magnesium Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 135-138
Author(s):  
Ming Bo Yang ◽  
Fu Sheng Pan ◽  
Yan Long Ma ◽  
Li Wen Tang
Keyword(s):  
Solid Solution ◽  
Magnesium Alloy ◽  
Solution Treatment ◽  
Experimental Alloy ◽  
Chinese Script ◽  
Research Results ◽  
Solid Solution Treatment

In this paper, the effects of Sb and RE on the solutionized microstructure and microhardness of Mg-6A1-1Zn-0.7Si magnesium alloy are investigated. The research results indicate that the solid solution treatment can result to the modification of Chinese script shaped Mg2Si phases in the microstructure of experimental alloy, and adding small amounts of RE and Sb can strengthen the modification efficiency. In addition, after the solid solution treatment at 420°C, the Mg-6A1-1Zn-0.7Si alloy added 0.4%Sb and 0.25%RE exhibits higher microhardness, but the effect of Sb and RE additions on the changing law between microhardness and solutionized time, is not obvious.

scholarly journals The Influence of Aluminum on the Microstructure and Hardness of Mg-5Si-7Sn Alloy

2016 ◽  
Vol 61 (1) ◽  
pp. 425-432 ◽  
Author(s):  
T. Rzychoń ◽  
B. Dybowski
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Magnesium Alloys ◽  
Solution Heat Treatment ◽  
Aerospace Industry ◽  
Solution Temperature ◽  
Precipitation Process ◽  
Low Density ◽  
Primary Crystals ◽  
Positive Effect

Magnesium alloys due the low density and good mechanical properties are mainly used in the automotive and aerospace industry. In recent years, magnesium alloys are extensively developed for use in high temperatures (above 120°C). Among these alloys, magnesium alloys containing tin and silicon have large possibilities of application due to the formation of thermally stable intermetallic Mg2Sn and Mg2Si. In this paper the influence of aluminum and heat treatment on the on the microstructure and hardness of Mg-7Sn-5Si alloy is reported. It was found that the microstructure of Mg-7Sn-5Si alloy consist of α-Mg solid solution, Mg2Sn and Mg2Si compounds. Addition of 2 wt% of Al to Mg-7Sn-5Si alloy causes the formation of Al2Sn phase. Moreover, Al dissolves in the α-Mg solid solution. The solution heat-treatment of tested alloys at 500°C for 24 h causes the dissolve the Mg2Sn phase in the α-Mg matrix and spheroidization of Mg2Si compound. The Mg2Si primary crystals are stable at solution temperature. After ageing treatment the precipitation process of equilibrium Mg2Sn phase was found in both alloys. The addition of aluminum has a positive effect on the hardness of Mg-7Sn-5Si alloy. In case of Mg-5Si-7Sn-2Al alloy the highest hardness was obtained for sample aged for 148 h at 250°C (88 HV2), while in case of Al-free alloy the highest hardness is 70 HV for material aged for 148 h at 250°C.

Effect of Ti, Al and Cu Addition on Structural Evolution and Phase Constitution of FeCoNi System Equimolar Alloys

2012 ◽  
Vol 724 ◽  
pp. 335-338 ◽  
Author(s):  
Xiao Wang ◽  
Hui Xie ◽  
Lei Jia ◽  
Zhen Lin Lu
Keyword(s):  
Solid Solution ◽  
Structural Evolution ◽  
Atomic Radius ◽  
Xrd Analysis ◽  
Entire Solution ◽  
Vacuum Arc ◽  
Mixing Enthalpy ◽  
Phase Constitution ◽  
Mixing Entropy ◽  
Coarse Dendrite

FeCoNi system equimolar alloys were fabricated by a vacuum arc melting. The phase constitution of FeCoNi system alloys was determined by XRD analysis and the microstructure was observed by OM. The comprehensive atomic radius δ, the mixing enthalpy ΔHmix and the mixing entropy ΔSmix of alloys were also calculated according to relevant equations. The results show that the addition of Ti, Al and Cu has an obvious influence on the microstructure and phase constitution of FeCoNi system equimolar alloys. Single Ti addition resulted in almost entire solid solution with a typical dendrite growth character and a little unknown phase. However, further addition of Al, Cu or Al+Cu into the FeCoNiTi equimolar alloys led to the occurrence of an entire solution phase with dendrite, coarse dendrite, and rosette dendrite respectively. Such a phenomena suggested that the mixing entropy caused by the increase of components number rather than the comprehensive atomic radius between the elements or the mixing enthalpy of the alloy systems might be responsible for the formation of almost entire solid solution in FeCoNi system equimolar alloys.

scholarly journals Ultrasonic processing of aluminium alloys above the liquidus: the role of Zr

2020 ◽  
Vol 326 ◽  
pp. 06002
Author(s):  
Dmitry Eskin
Keyword(s):  
Solid Solution ◽  
Aluminium Alloys ◽  
Eutectic Reaction ◽  
Structure Refinement ◽  
Al Alloys ◽  
Melt Processing ◽  
Ultrasonic Processing ◽  
Solution Type ◽  
Primary Crystals

Ultrasonic melt processing (USP) is gaining quite an interest in recent years due to the benefits of this technology to the melt quality and structure refinement. A number of mechanisms have been identified that govern the effects of USP at different stages of melt processing. Technologically it is advantageous to apply USP to the fluid melt rather than to a mushy solidifying alloy. In this case heterogeneous nucleation on available or activated/multiplied substrates is the main mechanism. Among these substrates, primary crystals of Al3Zr phase were shown to be potent and effective. This paper gives a review of the own research into the role of Al3Zr in structure refinement in various groups of Al alloys, from solid-solution type to hypereutectic. This overview includes the evidence of a possible eutectic reaction between Al and Al3Zr in Al-rich alloys, mechanisms of Al3Zr formation and refinement under USP (that enables these primary crystals to be active substrates for Al and some other primary phases), the role of USP in facilitating primary solidification of Al3Zr in the Al-Zr system, and the additional benefits of solute Ti presence. The paper is illustrated with the data obtained over the last 15 years of research led by the author.

Effects of Casting Temperature on as Cast Microstructure and Tensile Properties of AS31-Sr Alloy

2014 ◽  
Vol 915-916 ◽  
pp. 583-587 ◽  
Author(s):  
Jin Wei Wang ◽  
Ji Xue Zhou ◽  
Shou Qiu Tang ◽  
Fu Min Chu ◽  
Yuan Sheng Yang
Keyword(s):  
Elevated Temperature ◽  
Yield Strength ◽  
Ambient Temperature ◽  
Tensile Properties ◽  
Ultimate Strength ◽  
Mass Fraction ◽  
Casting Temperature ◽  
Chinese Script ◽  
Polyhedral Shape ◽  
Cast Microstructure

Casting temperature has important influence on microstructure and tensile properties of casting products. Effects of different casting temperatures (670°C, 700°C, 730°C and 760°C) on as cast microstructure and tensile properties both at ambient temperature and elevated temperature of AS31-0.1%Sr (mass fraction) alloy were studied.The experimental results show that there exist polyhedral shape, fine fibers shape and a few Chinese script Mg2Si particles in AS31-0.1%Sr alloys. The grains at the casting temperature of 700°C are finest. The ultimate strength,yield strength and elongation at both ambient temperature and 150°C first increase when the casting temperature increases from 670°C to 700°C and then decrease with the casting temperature continuously increasing to 760°C.

The Influence of Heat Treatment on the Microstructure and Hardness of Mg-5Si-7Sn-5Mn Alloy

2015 ◽  
Vol 229 ◽  
pp. 83-88
Author(s):  
Tomasz Rzychoń ◽  
Bartosz Chmiela ◽  
Adrian Mościcki ◽  
Bartłomiej Dybowski ◽  
Sylwia Jendrysko
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Intermetallic Compounds ◽  
Cast Alloy ◽  
Solution Treatment ◽  
Chinese Script

The microstructure and hardness of as-cast Mg-5Si-7Sn-5Mn alloy after solution and ageing treatments is presented in this paper. It was found that the microstructure of as-cast alloy. is composed of primary dendrites crystals of Mg2Si phase, α-Mg matrix, long needle-like precipitates of Mn5Si3, Chinese script particles of Mg2Si phase and irregular Mg2Sn phase. The solution treatment at 500°C causes the dissolution of the Mg2Sn phase in the α-Mg magnesium solid solution, whereas the remaining intermetallic compounds are stable in this temperature. The hardness of alloy increases from 73 HV2 to 96 HV2 at 250°C. The increase in hardness is a result of the formation of the lath-like precipitates of Mg2Sn phase within the α-Mg matrix.

Effect of Ultrasonic Vibration and Applied Pressure on the Microstructure and Mechanical Property of Al-5.0Cu-0.6Mn-0.6Fe Alloys

2016 ◽  
Vol 850 ◽  
pp. 559-565 ◽  
Author(s):  
Yu Liang Zhao ◽  
Yang Zhang ◽  
Zhi Luo ◽  
Zhi Wang ◽  
Wei Wen Zhang
Keyword(s):  
Mechanical Property ◽  
Ultrasonic Vibration ◽  
High Performance ◽  
Low Cost ◽  
Applied Pressure ◽  
Chinese Script ◽  
Process Technology ◽  
Polyhedral Shape ◽  
First Time ◽  
Microstructure And Mechanical Property

Al-5.0Cu-0.6Mn-0.6Fe alloy was obtained for the first time using ultrasonic vibration and squeeze casting simultaneously. The effect of ultrasonic vibration and applied pressure on the microstructures and hardness of Al-5.0Cu-0.6Mn-0.6Fe alloy were studied. The results indicated that the ultrasonic vibration and applied pressure promoted the formation of smaller α-Al globular grains. In particularly, with the treatment of ultrasonic vibration or applied pressure during solidification, the brittle Fe-rich imtermetallic compounds in Al-5.0Cu-0.6Mn-0.6Fe alloy became more refined and changed from Chinese script shape to polyhedral shape, which improved the mechanical property. Furthermore, these effects on the grain refinement and Fe-rich intermetallic compounds became more significant by using ultrasonic vibration and applied pressure concurrently during solidification. This process technology is helpful for the development of high performance aluminum alloys with low cost as well as for green casting.

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