scholarly journals EFFECT OF THE ADDITION OF LI ON THE STRUCTURE AND MECHANICAL PROPERTIES OF HYPOEUTECTIC Al-Mg2Si ALLOYS

2015 ◽  
Vol 55 (4) ◽  
pp. 253 ◽  
Author(s):  
Olena Prach ◽  
Jakub Horník ◽  
Kostiantyn Mykhalenkov

Alloys with various contents of Li were studied by means of  differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and energy dispersive X-Ray microanalysis (EDX).<br />The TEM investigations revealed that three different types of precipitation are formed in the alloy matrix during artificial aging. Two of the types represent different morphologies of Mg<sub>2</sub>Si precipitates. The appearance of the third type, identified as the δ-Al<sub>3</sub>Li phase, shows that the Al-Mg-Si system can be used successfully for designing an Li-containing casting alloy. However, this alloy has not yet been developed.

2015 ◽  
Vol 55 (4) ◽  
pp. 282 ◽  
Author(s):  
Oleksandr Trudonoshyn ◽  
Maxim Puchnin ◽  
Kostiantyn Mykhalenkov

<p>The as-cast and heat-treated structure of permanent mould castings of AlMg<sub>5</sub>Si<sub>2</sub>Mn alloys with different contents of Ti has been investigated by differential scanning calorimetry, hardness and microhardness measurements, tensile tests and fractography analyses, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. We have established that α-Al dendrites can be nucleated on an Al-Ti substrate, and also that primary Mg<sub>2</sub>Si crystals can be nucleated on oxides, including oxides of Al and Ti compounds. The dependence of the change in mechanical properties on ageing time, and on the amount of Ti in the alloys, is shown.</p>


Author(s):  
S. Fujishiro

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.


Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zaiqiang Feng ◽  
Mingqi Tang ◽  
...  

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.


2021 ◽  
pp. 095400832110055
Author(s):  
Yang Wang ◽  
Yuhui Zhang ◽  
Yuhan Xu ◽  
Xiucai Liu ◽  
Weihong Guo

The super-tough bio-based nylon was prepared by melt extrusion. In order to improve the compatibility between bio-based nylon and elastomer, the elastomer POE was grafted with maleic anhydride. Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA) were used to study the compatibility and micro-distribution between super-tough bio-based nylon and toughened elastomers. The results of mechanical strength experiments show that the 20% content of POE-g-MAH has the best toughening effect. After toughening, the toughness of the super-tough nylon was significantly improved. The notched impact strength was 88 kJ/m2 increasing by 1700%, which was in line with the industrial super-tough nylon. X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) were used to study the crystallization behavior of bio-based PA56, and the effect of bio-based PA56 with high crystallinity on mechanical properties was analyzed from the microstructure.


2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.


1991 ◽  
Vol 230 ◽  
Author(s):  
Toyohiko J. Konno ◽  
Robert Sinclair

AbstractThe crystallization of amorphous Si in a Al/Si multilayer (with a modulation length of about 120Å) was investigated using transmission electron microscopy, differential scanning calorimetry and X-ray diffraction. Amorphous Si was found to crystallize at about 175 °C with the heat of reaction of 11±2(kJ/mol). Al grains grow prior to the nucleation of crystalline Si. The crystalline Si was found to nucleate within the grown Al layers. The incipient crystalline Si initially grows within the Al layer and then spreads through the amorphous Si and other Al layers. Because of extensive intermixing, the original layered structure is destroyed. The Al(111) texture is also enhanced.


2008 ◽  
Vol 575-578 ◽  
pp. 941-946
Author(s):  
Hong Yan Tang ◽  
Ji Hui Wang ◽  
Guo Qiang Gao ◽  
Wen Xing Chen

Fiberglass continuous strand mat(CSM)/poly(urethane-isocyanurate) composites were formed by SRIM process, treated under different conditions and then characterized based on dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) ,transmission electron microscopy (TEM) and the mechanical property tests. The results show that the mechanical properties of the composites could be increased with improving the degree of microphase separation. At a given temperature (120°C), the degree of microphase separation is the highest for 4h and decreases gradually with prolonging treatment time. For a given time (4h), the well microphase-separated morphology is obtained and the degree of microphase mixing is increased at 120°C and 140°C treatments, respectively. The degree of microphase separation of the composites decreases with enhancing the temperature to 140°C.


Author(s):  
Mohammad K. Hossain ◽  
Samira N. Shaily ◽  
Hadiya J. Harrigan ◽  
Terrie Mickens

A completely biodegradable composite was fabricated from an herbal polymer, soy protein concentrate (SPC) resin. Soy protein was modified by adding 30 wt% of glycerol and 5 wt% of poly vinyl alcohol (PVA) to enhance its mechanical as well as thermal property. 3%, 5%, 10%, and 20% nanoclay (NC) were infused into the system. To evaluate its mechanical properties, crystallinity, thermal properties, bonding interaction, and morphological evaluation, tensile, X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR) tests, and optical microscopy (OM) and scanning electron microscopy (SEM) evaluation were performed. Tensile tests showed that the addition of nanoclay improved the mechanical properties of the modified resin. Soy protein is hydrophilic due to the presence of amino acids that contain various polar groups such as amine, carboxyl, and hydroxyl. As a result, polar nanoclay particles that are exfoliated can be evenly dispersed in the SPC resin. From experimental results, it is clear that adding of nanoclay with SPC resin significantly increased the stiffness of the SPC resin. A combination of 5% clay, 30% glycerol, and 5% PVA with the modified SPC resulted in the maximum stress of 18 MPa and Young modulus of 958 MPa. The modified SPC showed a reduced failure strain as well. X-ray diffraction curves showed an improvement of crystallinity of the prepared resin with increasing amount of nanoclay. Interaction among soy, glycerol, PVA, and nanoclay was clearly demonstrated from the FTIR analysis. Optical microscopy (OM) and scanning electron microscopy (SEM) micrographs revealed rougher surface in the nanoclay infused SPC samples compared to that of the neat one. SEM evaluation revealed rougher fracture surface in the NC infused samples.


2004 ◽  
Vol 19 (12) ◽  
pp. 3586-3591 ◽  
Author(s):  
Jiyang Chen ◽  
Ying Shi ◽  
Jianlin Shi

Nano-sized (Y,Gd)2O3:Eu powders were synthesized by a novel co-precipitation processing in which a mixture of ammonium hydroxide and ammonium hydrogen carbonate was adopted as a complex precipitant. Evolution behaviors of precursors during calcinations were studied by means of thermogravimetry-differential scanning calorimetry-mass spectrum, Fourier transform infrared, x-ray diffraction, scanning electron microscopy, and transmission electron microscopy in detail. Nano-sized (Y,Gd)2O3:Eu powder as prepared possessed a primary grain size of about 30 nm and specific surface area of 38 m2/g after being calcined at 850 °C for 2 h, showing much finer grains and less agglomeration. The as prepared nanopowder shows intense luminescence at 611nm under x-ray or ultraviolet excitation. Transparent (Y,Gd)2O3:Eu ceramics can also be fabricated using this high sinterable nanopowder.


2009 ◽  
Vol 24 (1) ◽  
pp. 39-49 ◽  
Author(s):  
J. Zhang ◽  
B. Liu ◽  
J.Y. Wang ◽  
Y.C. Zhou

Transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD) investigations were conducted on the hot-pressed Ti2SnC bulk ceramic. Microstructure features of bulk Ti2SnC ceramic were characterized by using TEM, and a needle-shaped β-Sn precipitation was observed inside Ti2SnC grains with the orientation relationship: (0001) Ti2SnC // (200) Sn and Ti2SnC // [001] Sn. With the combination of DSC and XRD analyses, the precipitation of metallic Sn was demonstrated to be a thermal stress-induced process during the cooling procedure. The reheating temperature, even as low as 400 °C, could trigger the precipitation of Sn from Ti2SnC, which indicated the low-temperature instability of Ti2SnC. A substoichiometry Ti2SnxC formed after depletion of Sn from ternary Ti2SnC phase. Under electron beam irradiation, metallic Sn was observed diffusing back into Ti2SnxC. Furthermore, a new Ti7SnC6 phase with the lattice constants of a = 0.32 and c = 4.1 nm was identified and added in the Ti-Sn-C ternary system.


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