Effect of Si, Sr Additions on Microstructure and Mechanical Properties of AZ91 Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 179-182
Author(s):  
S.B. Li ◽  
Zhi Wen Zou ◽  
Shou Mei Xiong
Keyword(s):  
Mechanical Properties ◽  
Silicon Content ◽  
Room Temperature ◽  
Chinese Script ◽  
Az91 Alloy ◽  
Permanent Mold ◽  
Remarkable Effect ◽  
Mg2si Phase ◽  
Β Phase ◽  
Si Content

In present work, Si and Sr elements were added into AZ91 alloy and cast directly into test samples using permanent mold. Mechanical properties of the samples at room temperature were evaluated by tensile test and the microstructure was analyzed. The results show that β-phase (Mg17Al12) of AZ91 alloy decreases with the addition of Si element and Mg2Si phase forms at the same time. Irregular Mg2Si phase precipitates preferentially at the grain boundaries at a low silicon content level. With the increase of the Si content, Mg2Si phase shows a complicated “Chinese- script” shape distributed at the grain boundary which leads to a lower ultimate tensile strength. Subsequently, the addition of Sr element has a remarkable effect on the form and distribution of Mg2Si phase of AZ91-Si alloys.

Mechanical Properties of AlSi9Mg Alloy with a Sodium Modifier

2014 ◽  
Vol 223 ◽  
pp. 78-86
Author(s):  
Tomasz Lipiński ◽  
Paweł Szabracki
Keyword(s):  
Mechanical Properties ◽  
Aluminium Alloys ◽  
Silicon Content ◽  
Eutectic Phase ◽  
Coarse Grained ◽  
Hypoeutectic Alloy ◽  
Β Phase ◽  
Two Component ◽  
Si Content ◽  
Direct Use

Al–Si alloys are among the most popular casting metals. Two-component aluminium alloys with silicon are not suitable for direct use after melting. Subject to their silicon content, Al Si alloys have a coarse-grained eutectic phase, and alloys with more than 13% Si content also feature large crystallites or β-phase needles. The β-phase is hard, but also fragile. Large crystallites are good planes of division, and they reduce the mechanical properties of alloys.In this study, the Al-9% Si alloy was refined with a sodium modifier. The modifier was added to the mould by the in-mould method. The modifier's influence on the microstructure and mechanical properties of the alloy was presented graphically. The results of the analysis indicate that the compound modifier influenced the evaluated properties of the Al-9%Si hypoeutectic alloy.

Effect of Sr and Nd on Microstructure and Mechanical Properties of AZ91-1Si Alloy

2009 ◽  
Vol 610-613 ◽  
pp. 765-770 ◽  
Author(s):  
Zhi Wen Zou ◽  
Shou Mei Xiong
Keyword(s):  
Mechanical Properties ◽  
Trace Elements ◽  
Intermetallic Compound ◽  
Grain Refinement ◽  
Room Temperature ◽  
Chinese Script ◽  
Mg2si Phase ◽  
Microstructure And Mechanical Properties ◽  
Refinement Mechanism ◽  
Morphology Modification

In present work, trace elements Sr and Nd were added into AZ91-1wt%Si alloys. The alloys were cast into a permanent mould and then machined into test bars. The microstructure and mechanical properties at room temperature of the specimens were investigated. Results showed that complicated Chinese script Mg2Si phase decreased in size with the increase of Sr addition. When Sr addition increased to 0.1wt%, the Mg2Si phase was changed from Chinese script shape into uniform polygon shape completely. At the same time, mechanical properties improved due to the morphology modification of the Mg2Si phase. An intermetallic compound containing Mg, Al, Nd and Si was found when Nd was added to the alloy. Remarkable modification on the shape and distribution of the Mg2Si phase was observed because of the intermetallic compound, which leads to a great change in mechanical properties. The grain refinement mechanism of Sr and Nd elements on the Mg2Si phase was discussed.

Permanent Mold Casting Practice and Microstructure and Mechanical Properties of Thin-Sectioned ADI Casting

2007 ◽  
Vol 26-28 ◽  
pp. 531-534
Author(s):  
B.M. Moon ◽  
Bong Hwan Kim ◽  
Je Sik Shin ◽  
Sang Mok Lee
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Ductile Cast Iron ◽  
Treatment Temperature ◽  
Chemical Compositions ◽  
Permanent Mold ◽  
Permanent Mold Casting ◽  
Treatment Practice ◽  
Mold Casting ◽  
Si Content

For thin-walled casting development of austempered ductile iron (ADI), permanent mold casting and accompanied heat treatment practice were systematically investigated to suppress and/or remove chill defects of ductile cast iron (DCI) with various thickness of 2 to 9 mm and to ensure mechanical properties of the final ADI casting. Si content was increased up to 3.8% to reduce the chill formation tendency under a high cooling rate. The residual Mg content remarkably affected the nodule count, while the nodule size and spherodization were proven to have weak relationships. Austenitizing process followed by austempering was very sensitive to chemical compositions (Si and Sn) and heat treatment temperature. As a practical application, the steel bar coupler for a structural frame was tried to produce without subsequent machining.

Effect of Silicon on the Microstructure, Tensile Properties and Hot Tearing Susceptibility of AZ91E Alloy

2012 ◽  
Vol 706-709 ◽  
pp. 3046-3051
Author(s):  
Comondore Ravindran ◽  
Sophie Lun Sin
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Tensile Properties ◽  
Room Temperature ◽  
Hot Tearing ◽  
Chinese Script ◽  
Az91 Alloy ◽  
Solidification Behavior ◽  
Last Stage ◽  
Hot Tearing Susceptibility

This Research Focused on Studying the Effect of Silicon on the Hot Tearing Susceptibility of Permanent Mould Cast AZ91E Magnesium Alloy. Varying Amounts of Silicon (0.5, 1.0 and 1.5 Wt.%) Were Added to AZ91E in the Form of an Al-53 Wt.% Si Master Alloy. the Microstructure, Grain Size and Solidification Behavior of each Alloy Were Characterized and Related to their Tensile Properties and Hot Tearing Susceptibility. the Results Showed that the Tensile Strength and the Elongation of AZ91 Alloy Decreased with the Addition of Silicon at Room Temperature, due to the Formation of Chinese Script Mg2si Particles. however, Silicon Significantly Reduced the Hot Tearing Susceptibility of AZ91E. this Was Attributed to the Reduction of the Grain Size and the Decreased Freezing Range of AZ91E, which Contributed to Improve the Interdendritic Feeding during the Last Stage of Solidification.

Influences of Solution Temperatures on Microstructure and Mechanical Properties of near α Titanium Alloy

2021 ◽  
Vol 1035 ◽  
pp. 89-95
Author(s):  
Chao Tan ◽  
Zi Yong Chen ◽  
Zhi Lei Xiang ◽  
Xiao Zhao Ma ◽  
Zi An Yang
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
High Temperature ◽  
Room Temperature ◽  
Solution Temperature ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Β Phase ◽  
Α Phase ◽  
New Type

A new type of Ti-Al-Sn-Zr-Mo-Si series high temperature titanium alloy was prepared by a water-cooled copper crucible vacuum induction melting method, and its phase transition point was determined by differential thermal analysis to be Tβ = 1017 °C. The influences of solution temperature on the microstructures and mechanical properties of the as-forged high temperature titanium alloy were studied. XRD results illustrated that the phase composition of the alloy after different heat treatments was mainly α phase and β phase. The microstructures showed that with the increase of the solution temperature, the content of the primary α phase gradually reduced, the β transformation structure increased by degrees, then, the number and size of secondary α phase increased obviously. The tensile results at room temperature (RT) illustrated that as the solution temperature increased, the strength of the alloy gradually increased, and the plasticity decreased slightly. The results of tensile test at 650 °C illustrated that the strength of the alloy enhanced with the increase of solution temperature, the plasticity decreased first and then increased, when the solution temperature increased to 1000 °C, the alloy had the best comprehensive mechanical properties, the tensile strength reached 714.01 MPa and the elongation was 8.48 %. Based on the room temperature and high temperature properties of the alloy, the best heat treatment process is finally determined as: 1000 °C/1 h/AC+650 °C/6 h/AC.

Effects of Microstructure and Partial Melting on Tensile Properties of AZ91 Magnesium Cast Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 65-68 ◽  
Author(s):  
Tian Ping Zhu ◽  
Zhan W. Chen ◽  
Wei Gao
Keyword(s):  
Mechanical Properties ◽  
Partial Melting ◽  
Tensile Properties ◽  
Cast Alloy ◽  
Az91 Alloy ◽  
Β Phase ◽  
Interdendrite Region ◽  
Mg17al12 Phase ◽  
Az91 Magnesium ◽  
Cast Microstructure

Mechanical properties of AZ91 cast alloy depend strongly on the morphology (size and distribution) of the second (β-Mg17Al12) phase. It was observed that low ductility of AZ91 alloy was attributed to the brittle nature of the β phase particles at which microcracks initiated. These microcracks then coalesced contributing to the fracture of alloy. Quantitative study on microcracking progress revealed that cast samples with coarse microstructures fractured at low strain due to the non-uniform distribution of bulk blocky β particles at interdendrite region. These fracture surfaces exhibited clear cleavage mode. Fine cast microstructure presented quasicleavage fracture mode with clear dimple and tear ridges. The partial melting (and resolidification) heat treatment improved tensile properties, which was in disagreement with the available data from literature.

The Properties of CrSiN Coatings of Different Si Content

2014 ◽  
Vol 687-691 ◽  
pp. 4323-4326 ◽  
Author(s):  
Xiang Min Xu ◽  
Hao Zhang ◽  
Fei Fei Luo ◽  
Zi Hao Zhou ◽  
Shu Wang Duo
Keyword(s):  
Mechanical Properties ◽  
Magnetron Sputtering ◽  
Amorphous Phase ◽  
Deposition Rate ◽  
Comparative Studies ◽  
Silicon Content ◽  
Amorphous Structure ◽  
Closed Field ◽  
Reactive Magnetron ◽  
Si Content

CrSiN coatings of different silicon content were deposited on 1Cr18Ni9Ti austenitic stainless by d.c. reactive magnetron sputtering in a closed field unbalanced system. Comparative studies on microstructure and mechanical properties between CrN and CrSiN coatings with various Si contents were carried out. The structure of the CrSiN coatings was found to change from crystalline to amorphous structure as the Si contents increased. Amorphous phase of Si3N4 compound was suggested to exist in the CrSiN coatings. The crystalline grain became smaller in CrSiN coatings. With the increasing Si content, the coating deposition rate slew down, while the hardness of coatings improved obviously and the best hardness was about 4200 HV0.01 when the Si content was 1.13%.

Effect of Ti Addition on the Microstructure and Mechanical Properties of Cast AZ91 Magnesium Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 3819-3823 ◽  
Author(s):  
Xiu Lan Ai ◽  
Gao Feng Quan ◽  
Jun Yang ◽  
Zhao Ming Liu
Keyword(s):  
Mechanical Properties ◽  
Small Addition ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Β Phase ◽  
Maximum Value ◽  
Az91 Magnesium ◽  
Microstructure And Mechanical Property ◽  
Ti Addition ◽  
Cast Microstructure

Ti addition to AZ91 alloy has been investigated with conventional casting. The microstructure and mechanical property were examined. The results show that addition of Ti with an amount of 0.1~0.5%wt resulted in a refinement of the as-cast microstructure. The morphology of β phase is changed from coarse, uneven, semi-continuous skeletal network to small, uniform, short rod-like or granular. When the content of Ti is 0.4wt%, the tensile strength and elongation go up to maximum value of 197 MPa and 6.9% respectively. Small addition of 0.2%wt Ti to AZ91 alloy predominantly forms TiAl3phase, lying in β-phases at the grain boundaries. The mechanism of mechanical properties improvement caused by Ti addition is discussed.

Effects of Aluminum Content on the As-Cast Microstructure and Mechanical Properties of Mg-xAl-0.7Si Based Alloys

2007 ◽  
Vol 546-549 ◽  
pp. 191-194
Author(s):  
Ming Bo Yang ◽  
Fu Sheng Pan ◽  
Liang Bai ◽  
Ren Ju Cheng
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Xrd Analysis ◽  
Chinese Script ◽  
X Ray Diffraction ◽  
Mg2si Phase ◽  
Al Content ◽  
Microstructure And Mechanical Properties ◽  
Mg17al12 Phase ◽  
Cast Microstructure

The effects of the Al content on the as-cast microstructure and mechanical properties of Mg-xAl-0.7Si based magnesium alloys which contained 1%Zn, 0.25%Mn, 0.4%Sb and 0.25%RE were investigated by optical microscopy(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD) analysis and tensile testing. The results indicated that the effects of the Al content from 6% to 8% on the alloy phase types of the experimental alloys were not obvious, and the as-cast microstructure of the experimental alloys with different Al content were composed mainly of the α-Mg matrix, Mg17Al12 phase, Mg2Si phase and Mg3Sb2 phase. The Chinese script morphology of the Mg2Si phase was very obvious in the experimental alloy with 6%Al. With the increase of Al content from 6% to 8%, the yield strength of the experimental Mg-xA1-0.7Si based alloys at room temperature increased, but the yield strength of the experimental Mg-xA1-0.7Si based alloys at 150 °C decreased.

scholarly journals Tensile Mechanical Properties and Strengthening Mechanism of Hybrid Carbon Nanotube and Silicon Carbide Nanoparticle-Reinforced Magnesium Alloy Composites

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Xia Zhou ◽  
Depeng Su ◽  
Chengwei Wu ◽  
Liming Liu
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Magnesium Alloy ◽  
Room Temperature ◽  
Hybrid Composites ◽  
Coefficient Of Thermal Expansion ◽  
Strengthening Mechanism ◽  
Az91 Alloy ◽  
Az91 Magnesium Alloy ◽  
Sic Nanoparticles

AZ91 magnesium alloy hybrid composites reinforced with different hybrid ratios of carbon nanotubes (CNTs) and silicon carbide (SiC) nanoparticulates were fabricated by semisolid stirring assisted ultrasonic cavitation. The results showed that grains of the matrix in the AZ91/(CNT + SiC) composites were obviously refined after adding hybrid CNTs and SiC nanoparticles to the AZ91 alloy, and the room-temperature mechanical properties of AZ91/(CNT + SiC) hybrid composites were improved comparing with the unreinforced AZ91 matrix. In addition, the tensile mechanical properties of the AZ91 alloy-based hybrid composites were considerably improved at the mass hybrid ratio of 7 : 3 for CNTs and SiC nanoparticles; in particular, the tensile and yield strength were increased, respectively, by about 45 and 55% after gravity permanent mould casting. The reason for an increase in the room-temperature strength of the hybrid composites should be mainly attributable to the larger hybrid ratio of CNTs and SiC nanoparticles, the coefficient of thermal expansion (CTE) mismatch between matrix and hybrid reinforcements, the dispersive strengthening effects (Orowan strengthening), and the grain refining (Hall-Petch effect).

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