Synthesis, Microstructure, and Mechanical Properties of FeCo-VC Composites

2006 ◽  
Vol 980 ◽  
Author(s):  
Hongbin Bei ◽  
E. P. George

AbstractFe-Co-V-C quaternary alloys were drop cast and directionally solidified to obtain an in situ composite. It is found that the fully eutectic structure occurs at a composition of Fe - 40.5Co -10.4V- 8.6C (at. %) in a drop-cast alloy. Directional solidification of this composition in a high-temperature optical floating zone furnace produces a well-aligned microstructure, consisting of sub-micron VC fibers (~19% by volume) embedded in a FeCo-5V solid solution matrix containing ~ 1% C. The temperature dependencies of mechanical properties of this composite were examined by tensile tests and the composite was found to have higher yield strength and lower ductility than the matrix.

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 172 ◽  
Author(s):  
Ming Li ◽  
Zhiming Shi ◽  
Xiufeng Wu ◽  
Huhe Wang ◽  
Yubao Liu

In this work, the microstructure of Al-5Fe-1.5Er alloy was characterized and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) techniques. The effect of microstructure on the behavior of crack initiation and propagation was investigated using in situ tensile testing. The results showed that when 1.5 wt.% Er was added in the Al-5Fe alloy, the microstructure consisted of α-Al matrix, Al3Fe, Al4Er, and Al3Fe + Al4Er eutectic phases. The twin structure of Al3Fe phase was observed, and the twin plane was {001}. Moreover, a continuous concave and convex interface structure of Al4Er was observed. Furthermore, Al3Fe was in the form of a sheet with a clear gap inside. In situ tensile tests of the alloy at room temperature showed that the crack initiation mainly occurred in the Al3Fe phase, and that the crack propagation modes included intergranular and trans-granular expansions. The crack trans-granular expansion was due to the strong binding between Al4Er phases and surrounding organization, whereas the continuous concave and convex interface structure of Al4Er provided a significant meshing effect on the matrix and the eutectic structure.


2013 ◽  
Vol 312 ◽  
pp. 315-318 ◽  
Author(s):  
C.F. Fang ◽  
L.G. Meng ◽  
N.N. Wu ◽  
X.G. Zhang

In-situ micro/nanosized TiB2 and Al2(Y, Gd) particles reinforced magnesium matrix composite was successfully fabricated by addition of Al-Ti-B preform into Mg-Gd-Y-Zn matrix alloy, its microstructures and properties were investigated. The results show that the introduction of Al-Ti-B preform causes the precipitation of Al2(Y, Gd) particles and the SHS synthesis of TiB2 particles which significantly refine solidification structure. The reinforced Al2(Y, Gd) particles with average sizes of 5-8 μm are uniformly distributed throughout the magnesium matrix, and have a good bond to the matrix. Tensile tests indicate that, compared with the former matrix alloy, mechanical properties of the multiple in-situ particles reinforced composite are improved all-roundly.


2015 ◽  
Vol 727-728 ◽  
pp. 111-114 ◽  
Author(s):  
Li Yuan Sheng ◽  
Fang Yang ◽  
Ting Fei Xi

In the present paper, the Mg-Zn-Y-Nd alloy is fabricated by as casting and hot extrusion. Microstructure and mechanical properties of the as-cast, heat treated and hot extruded alloys are investigated. The results exhibit that Mg24Y5 phase with eutectic structure forms in the as-cast alloy, which has an orientation relationship with matrix of . The precipitating phase separates the matrix semi-continuously. The heat treatment results in most precipitates solid soluted into matrix, but there are still some nanoscale particles and residual phase along grain boundary. The hot extrusion refines the microstructure and leads to the formation of stacking faults in the matrix. Compared with the as-cast and heat treated alloy, the hot extruded alloy obtain great improvement in mechanical properties, which should be attributed to the grain refinement, solid solution and fomation of crystal defects


2014 ◽  
Vol 988 ◽  
pp. 156-160
Author(s):  
Hong Wei Liu ◽  
Feng Wang ◽  
Bai Qing Xiong ◽  
Yong An Zhang ◽  
Zhi Hui Li ◽  
...  

The microstructure and mechanical properties of the Al-2.24Cu-1.42Mg-0.9Fe-0.9Ni alloy were studied using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and tensile tests. The results indicate that the microstructures of the as cast alloy involve α-Al matrix, Al/Al2CuMg eutectic structure, Al7Cu2Fe, Al7Cu4Ni and Al9FeNi compounds. The tensile test results indicate that the alloy at elevated temperature (200°C) displays superior tensile strength due to the presence of the thermally stable Al7Cu2Fe, Al7Cu4Ni and Al9FeNi compounds.


2019 ◽  
Vol 950 ◽  
pp. 15-23
Author(s):  
Ting Li ◽  
Zhi Wei Du ◽  
Wei Liu ◽  
Jia Wei Yuan ◽  
Kui Zhang ◽  
...  

This paper proposes a two-step homogenization heat treatment to dissolve the eutectic structure and long period stacking ordered phase (LPSO) formed during solidification into the α-Mg matrix. The microstructure evolution and mechanical properties of Mg–7Gd–3Y–1Nd–2Zn–0.5Zr alloy during the two-step homogenization heat treatment have been investigated systemically. The results reveal that as-cast alloy is composed mainly of α-Mg, (Mg,Zn)3RE, eutectic phase, stacking fault, block-like LPSO phase and square-shaped compounds rich in RE. The HRTEM results suggest that the block-like long period stacking ordered phase in as-cast alloy is 14H-type rather than 18R structure, and the stacking sequences of the 14H-LPSO phase are ABABACBCBCBCAB. After the first step homogenization of 520°C for 48 h, the eutectic structure has dissolved into the matrix, whereas the 14H-LPSO phase remains in the alloy. To further dissolve the LPSO phase into matrix, the second step homogenization of 540°C for 24h was adopted. After the second-step of homogenization, the residual 14H-LPSO phase has dissolved into the matrix totally. The as-homogenized alloy is composed mainly of α-Mg and square-shaped compounds rich in RE. The tensile tests at room temperature (RT) exhibit that the ultimate tensile strength (UTS), yield strength (YS) and elongation of as-cast alloy are 172 MPa, 128MPa and 2.8%, whereas the UTS, YS and elongation of as-homogenized alloy are 253 MPa, 185 MPa and 8.4, respectively.


Author(s):  
Ming Li ◽  
Zhiming Shi ◽  
Xiufeng Wu ◽  
Huhe Wang ◽  
Yubao Liu

The microstructure of Al-5Fe-1.5Er alloy was characterized and analyzed by using XRD, SEM, TEM and EDS. The effect of microstructure on the behavior of crack initiation and propagation was investigated by in situ tensile testing. Results show that the microstructure consists of α-Al matrix, Al3Fe, Al4Er, eutectic phase Al3Fe + Al4Er, while the 1.5 wt.% Er was added in Al-5Fe alloy. The twin structure of the Al3Fe phase was observed, and the twin plane is {001}. Moreover, a continuous concave and convex interface structure of the Al4Er has been found. Al3Fe is in the form of a sheet with a clear gap inside.In situ tensile tests of the alloy at room temperature show that the crack initiation occured mainly in the Al3Fe phase, and that the crack propagation modes include intergranular and transgranular expansion. Crack transgranular expansion is due to the strong binding ability between Al4Er phases and surrounding organization, and the continuous concave and convex interface structure of the Al4Er provides a significant meshing effect on the matrix and eutectic structure.


2006 ◽  
Vol 980 ◽  
Author(s):  
Sujing Xie ◽  
Easo P. George

AbstractA series of binary V-B alloys, with compositions spanning the eutectic, were produced by arc melting and drop casting. Microstructural examination revealed that the fully eutectic structure occurs at V-11B rather than V-15B as reported in the V-B phase diagram (all compositions in at.%). The V-11B eutectic was directionally solidified in an optical floating zone furnace, resulting in a composite microstructure consisting of a V matrix and flake or trigonal shaped V3B2 phase. The boride flake spacing (ë) decreases with increasing growth rate (R), following the relation ë2.56R=C, where C is a constant. TEM observations showed that the orientation relationship between the V and V3B2 phases is given by: [001]V // [001]V3B2 and (100)V // (100)V3B2. The growth direction and the V/V3B2 interface are parallel to the [001] direction and (100) planes in the two phases, respectively. Tensile tests were used to investigate the temperature dependence of the strength and ductility of the composite. At temperatures to 600°C, the yield strength of the eutectic is about 140 MPa higher than that of a commonly used vanadium solid-solution alloy, V-4Cr-4Ti. Surprisingly, the eutectic shows 5% tensile ductility at room temperature which increases to 10% as the test temperature is raised to 800°C.


Author(s):  
Rama Rao Panugothu ◽  
Bhaskar Majumdar ◽  
Anil Kumar Bhatnagar

The developed microstructure features a long with mechanical properties in vacuum brazing of commercially pure Ti-alloy using Ti20Zr20Cu60-x-Nix (x=10, 20, 30, 40 and 50) metallic filler. Brazing temperatures and holding times employed in this study were 1240-1279 K (967-1006oC) for a period of 10 min, respectively. The mechanical properties of brazed joints were evaluated by nanoindention at a constant peak load of 5000 μN and tensile tests. The number of intermetallic phase, such as NiTi2, Ti2Cu, (Ti, Zr)2Cu, (Ti, Zr)2Ni, β(Ti, Zr), α-Ti and NiTi. The solid solution matrix have been identified at 1279 K out of these different regions the NiTi2 rich region had the highest nanohardness of 17 GPa, It is interesting to note that among five different glasses, the Ti20Zr20Cu10Ni50 has the highest yield strength of 17 GPa, which is mainly due to NiTi2 phase. Based on the tensile test results all cracks propagate along the brittle intermetallic compounds like NiTi2 in the reaction layer the reduction of the strength of the joints and fracture behaviour upon propagation of the crack, which shows the morphological cleavage including facets characteristics.


2005 ◽  
Vol 475-479 ◽  
pp. 317-320 ◽  
Author(s):  
Jing Pei Xie ◽  
Ji Wen Li ◽  
Zhong Xia Liu ◽  
Ai Qin Wang ◽  
Yong Gang Weng ◽  
...  

The in-situ Ti alloying of aluminium alloys was fulfilled by electrolysis, and the material was made into A356 alloy and used in automobile wheels. The results show that the grains of the A356 alloy was refined and the second dendrites arm was shortened due to the in-situ Ti alloying. Trough 3-hour solution treatment and 2-hour aging treatment for the A356 alloy, the microstructures were homogeneous, and Si particles were spheroid and distribute in the matrix fully. The outstanding mechanical properties with tensile strength (σb≥300Mpa) and elongation values (δ≥10%) have been obtained because the heat treatment was optimized. Compared with the traditional materials, tensile strength and elongation were increased by 7.6~14.1% and 7.4~44.3% respectively. The qualities of the automobile wheels were improved remarkably.


Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1074
Author(s):  
Jacopo Donnini ◽  
Francesca Bompadre ◽  
Valeria Corinaldesi

The use of Fabric-Reinforced Cementitious Matrix (FRCM) systems as externally bonded reinforcement for concrete or masonry structures is, nowadays, a common practice in civil engineering. However, FRCM durability against aggressive environmental conditions is still an open issue. In this paper, the mechanical behavior of a glass FRCM system, after being subjected to saline, alkaline and freeze–thaw cycles, has been investigated. The experimental campaign includes tensile tests on the fabric yarns, compression and flexural tests on the matrix and tensile tests (according to AC434) on FRCM prismatic coupons. The effects of the different environmental exposures on the mechanical properties of both the constituent materials and the composite system have been investigated and discussed. Ion chromatography analysis has also been performed to better understand the damage mechanisms induced by environmental exposures and to evaluate the ions’ penetration within the inorganic matrix. Alkaline exposure was shown to be the most detrimental for Alkali-Resistant (AR) glass fiber yarns, causing a reduction in tensile strength of about 25%. However, mechanical properties of the FRCM composite seemed not to be particularly affected by any of the artificial aging environments.


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