Effect of Sr Addition on Microstructure and Mechanical Properties of Semi-Solid 2024 Al Alloys

2014 ◽  
Vol 496-500 ◽  
pp. 336-339
Author(s):  
Nisachon Khunbanterng ◽  
Sirikul Wisutmethangoon ◽  
Thawatchai Plookphol ◽  
Jessada Wannasin

Semi-solid 2024 Al alloys with strontium (Sr) addition of 0.15 wt% and 0.3 wt% were prepared by Gas Induced Semi-Solid (GISS) process. Effect of Sr addition on the microstructure and mechanical properties of the semi-solid 2024 alloy was investigated. It was found that the tensile strength and % elongation of the T6 heat treated alloy with the Sr addition were higher than those without Sr addition owing to the reduction of Mg2Si phase formation. The semi-solid 2024 Al alloy with 0.15%Sr addition obtained the average highest tensile strength of 382 MPa and elongation of 6.45%.

2014 ◽  
Vol 893 ◽  
pp. 353-356
Author(s):  
Atchara Sangchan ◽  
Thawatchai Plookphol ◽  
Jessada Wannasin ◽  
Sirikul Wisutmethangoon

Effect of strontium (Sr) addition on the microstructure and the mechanical properties of semi-solid A356 aluminum alloy produced by GISS process were investigated in this study. Strontium addition resulted in both grain refinement and modification of eutectic Si. The maximum average ultimate tensile strength and elongation of 291.06 MPa and 17.31%, respectively, were obtained from the T6 heat-treated specimen containing 0.08wt%Sr. The excessive addition of strontium (0.2wt%Sr), however, seemed to deteriorate the mechanical properties of the alloy as a result of the Al2Si2Sr particle formation.


Author(s):  
S C Sharma

A well-consolidated composite of Al alloy 6061 reinforced with 4, 8 and 12 wt% garnet was prepared by a liquid metallurgy technique, the composite was heat treated for different ageing durations (T6 treatment), and its mechanical properties were determined by destructive testing. The results of the study indicated that, as the garnet particle content in the composites increased, there were marked increases in the ultimate tensile strength, compressive strength and hardness but there was a decrease in the ductility. There was an improvement in the tensile strength, compressive strength, and hardness with ageing due to precipitation. Precipitation in Al alloy 6061, with and without garnet particulate reinforcement, was studied using transmission electron microscopy. The fracture behaviour of the composites was altered significantly by the presence of garnet particles and the crack propagation through the matrix, and the reinforcing particle clusters resulted in final fracture.


2014 ◽  
Vol 217-218 ◽  
pp. 332-339 ◽  
Author(s):  
Xiao Kang Liang ◽  
Da Quan Li ◽  
Pascal Côté ◽  
Stephen P. Midson ◽  
Qiang Zhu

The spheroidal grains in billets used for semi-solid casting are generally manufactured by electromagnetic stirring (EMS) during the casting process. This method however, is not economically applicable for small quantities of the thixo billets. Swirled Enthalpy Equilibration Device (SEED) has been developed as a rheocasting process, and the SEED process is of interest for developing new thixo alloys, as well as for optimizing the thixocasting processes for high quality components. The objective of this paper is to compare the microstructure and mechanical properties of aluminum alloy 319s billets and castings produced using EMS and SEED feed materials. The experimental results show that for as-cast billets made from SEED process, a well-developed spheroidal grain structure is distributed throughout the cross-section of the billet, while for as-cast EMS billets, the grain structure is inhomogeneous, i.e., a dendritic structure was present adjacent to the surface of the billet, while a uniform, spheroidal structure was present at the centre. After the thixocasting process, however, the both SEED and EMS billets have well-developed, spheroidal grain structures. Mechanical properties of thixocast and T61 heat treated components are comparable for the both SEED and EMS billets.


2014 ◽  
Vol 900 ◽  
pp. 141-145 ◽  
Author(s):  
Can Feng Fang ◽  
Guang Xu Liu ◽  
Ling Gang Meng ◽  
Xing Guo Zhang

The effects of in-situ TiB2 particle fabricated from Al-Ti-B system via the self-propagating high-temperature synthesis (SHS) reaction technology on microstructure and mechanical properties of Mg-Sn-Zn-Al alloy were investigated. The results indicate that the size of the Mg2Sn and α-Mg+Mg32(Al,Zn)49 phase becomes coarser with the increasing content of Al-Ti-B preform, meanwhile the amount of eutectic α-Mg+Mg32(Al,Zn)49 phase increases too. The addition of Al-Ti-B is favorable toward promoting the strength of composites, but deteriorates elongation. The resulting as-extruded composite material with 4 wt.% Al-Ti-B preform exhibits good overall mechanical properties with an ultimate tensile strength of 291 MPa and an elongation over 2 %.


2017 ◽  
Vol 898 ◽  
pp. 104-110 ◽  
Author(s):  
Peng Qi ◽  
Bo Long Li ◽  
Wen Jian Lv ◽  
Tong Bo Wang ◽  
Zuo Ren Nie

The effect of the different electromagnetic stirring frequency after low temperature pouring on microstructures and mechanical properties of Al-7Si-0.42 Mg-0.1Cu alloys was studied. It was found that the primary α-Al becomes smaller and tended to be spherical morphology, and the particles were uniformly distributed after electromagnetic stirring. The tensile strength of alloys improved gradually from 193.02 MPa to 212.54 MPa, and the elongation increased from 3.73% to 6.67% when the stirring frequency was 10 Hz. From the fracture morphology, the fracture for alloy stirred at frequency of 10 Hz showed more dimples than that without stirring. When the stirring frequency increased to 15 Hz, the microstructures of primary α-Al appeared to be dendritic structures, and the grains became coarse. As a result, the 10 Hz was the best electromagnetic stirring frequency.


Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 318
Author(s):  
Yajun Yu ◽  
An Du ◽  
Xue Zhao ◽  
Yongzhe Fan ◽  
Ruina Ma ◽  
...  

This paper proposes a simple reactive melt infiltration process to improve the mechanical properties of silicon carbide (SiC) ceramics. SiC matrix composites were infiltrated by Al–Si (10 wt.%)–xTi melts at 900 °C for 4 h. The effects of Ti addition on the microstructure and mechanical properties of the composites were investigated. The results showed that the three-point bending strength, fracture toughness (by single-edge notched beam test), and fracture toughness (by Vickers indentation method) of the SiC ceramics increased most by 34.3%, 48.5%, and 128.5%, respectively, following an infiltration with the Al–Si (10 wt.%)–Ti (15 wt.%) melt. A distinct white reaction layer mainly containing a Ti3Si(Al)C2 phase was formed on the surface of the composites infiltrated by Al alloys containing Ti. Ti–Al intermetallic compounds were scattered in the inner regions of the composites. With the increase in the Ti content (from 0 to 15 wt.%) in the Al alloy, the relative contents of Ti3Si(Al)C2 and Ti–Al intermetallic compounds increased. Compared with the fabricated composite infiltrated by an Al alloy without Ti, the fabricated composites infiltrated by Al alloys containing Ti showed improved overall mechanical properties owing to formation of higher relative content Ti3Si(Al)C2 phase and small amounts of Ti–Al intermetallic compounds.


2014 ◽  
Vol 788 ◽  
pp. 215-222
Author(s):  
Yong Peng ◽  
Shun Cheng Wang ◽  
Hai Tao Zhou ◽  
Kai Hong Zheng ◽  
He Xing Chen

The effect of applied forging pressure on microstructure and mechanical properties of 6061 aluminum alloy was examined. The results showed that the ultimate tensile strength, elongation and hardness of the alloy after heat-treated treatment increase with the applied forging pressure, and the corresponding highest values, 365MPa, 11.52% and 146.53HV, were obtained at the applied forging pressure of 120MPa. Compared to casting condition without forging pressure, the ultimate tensile strength, elongation and hardness can be increased by 22.8%, 98.2% and 48.7%, respectively. The defects such as the shrinkage pores and cracks were absent in the microstructure due to the applied forging pressure. The SEM observation indicated that the fracture mode of 6061 aluminum alloy is more ductile at higher applied forging pressure.


2020 ◽  
Vol 34 (25) ◽  
pp. 2050261
Author(s):  
Yingwu Wang ◽  
Xiaoqing Zuo ◽  
Songjiang Ran ◽  
Yushun Ye ◽  
Jihua Tian

The effects of semi-solid extrusion temperature change, extrusion pressure, SiC content and T5 heat treatment on the microstructure, mechanical properties, and wear resistance of SiC particle strengthened high aluminum zinc-base alloy [Formula: see text] composites were studied. The results show that semi-solid extrusion broke the dendrites of [Formula: see text] composites, refined their grain structure, and improved particle aggregation. The density, hardness, yield strength, tensile strength and elongation of [Formula: see text] composites first increased and then decreased when the extrusion temperature and SiC content increased, and also increased when the extrusion pressure rose. The optimal extrusion temperature, pressure and SiC content are 475[Formula: see text], 15 MPa and 10 wt.%, respectively. T5 heat treatment further refined the crystalline grains and promoted [Formula: see text] and [Formula: see text] to precipitate as strengthening phases, which improve the mechanical properties and wear resistance of [Formula: see text] composites. Consequently, the hardness, yield strength, tensile strength and elongation of the heat-treated composites improved by 18.99%, 9.66%, 4.93% and 9.76%, respectively. The wear loss of the heat-treated composites reduced by 31.65% under a load of 1600 N and a rotational speed of 200 r/min compared with the as-cast composites.


2018 ◽  
Vol 775 ◽  
pp. 459-465 ◽  
Author(s):  
Zhi Cheng Lu ◽  
Zhen Lin Liu ◽  
Dan Wu ◽  
Yong Liang Li ◽  
Wei Shen ◽  
...  

In this paper, the effect of Al content on the recrystallization behavior and mechanical properties of Pb-Al alloys were studied. The segregation behavior of Al in Pb-Al alloy was investigated. Moreover, the microstructures and precipitates of the alloys were also studied. The results show that the addition of Al can affect the recrystallization behavior of lead and improve its tensile strength. The recrystallization grains are effectively refined with the addition of 0.05%Al and the tensile strength increases obviously. However, the Al-rich phase grows significantly and its refinement effect is reduced with further increasing the Al content, thus, the tensile strength decreases. The mechanical stirring can effectively decrease the segregation degree of Al in Pb-Al alloys, but the yield of Al reduces. After the mechanical stirring, the sizes of Al phases decrease and theirs distribution is more uniform.


Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2126 ◽  
Author(s):  
Shikai Zhang ◽  
Pan Ma ◽  
Yandong Jia ◽  
Zhishui Yu ◽  
Rathinavelu Sokkalingam ◽  
...  

In this study, a combination of Al–12Si and Al–20Si (Al–(12-20)Si) alloys was fabricated by selective laser melting (SLM) as a result of increased component requirements such as geometrical complexity and high dimensional accuracy. The microstructure and mechanical properties of the SLM Al–(12-20)Si in as-produced as well as in heat-treated conditions were investigated. The Al–(12-20)Si interface was in the as-built condition and it gradually became blurry until it disappeared after heat treatment at 673 K for 6 h. This Al–(12-20)Si bi-material displayed excellent mechanical properties. The hardness of the Al–20Si alloy side was significantly higher than that of the Al–12Si alloy side and the disparity between both sides gradually decreased and tended to be consistent after heat treatment at 673 K for 6 h. The tensile strength and elongation of the Al–(12-20Si) bi-material lies in between the Al–12Si and Al–20Si alloys and fracture occurs in the Al–20Si side. The present results provide new insights into the fabrication of bi-materials using SLM.


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