Microstructural Evolution during Partial Remelting of 6061 Aluminum Bulk Alloy Prepared by Cold-Pressing of Alloy Powder

2013 ◽  
Vol 820 ◽  
pp. 20-24 ◽  
Author(s):  
Yu Shi Chen ◽  
Ti Jun Chen ◽  
Wei Fu ◽  
Pu Bo Li
Keyword(s):  
Microstructural Evolution ◽  
Heating Temperature ◽  
Spherical Particles ◽  
Bulk Alloy ◽  
Cold Pressing ◽  
Partial Remelting ◽  
Coarsening Behavior ◽  
Primary Particles ◽  
Rapid Coarsening ◽  
Cold Pressed

The microstructural evolution was investigated during partial remelting of 6061 aluminum bulk alloy prepared by cold-pressing of atomized alloy powders. Meanwhile, the effect of heating temperature on semisolid microstructure was also studied. It was found that after partial remelted, a semisolid microstructure with small and nearly spherical particles can be obtained. The microstructural evolution can be divided into three stages: the rapid coarsening of grains and powders, the structure separation and spheroidization of powders, and the final coarsening behavior of primary particles. For most of the primary particles (larger than 10 μm) in the semisolid state, one particle originates from one original powder in the cold-pressed bulk alloy. Furthermore, proper elevated the heating temperature is beneficial to obtain ideal semisolid microstructure.

scholarly journals Semisolid Microstructural Evolution during Partial Remelting of a Bulk Alloy Prepared by Cold Pressing of the Ti-Al-2024Al Powder Mixture

Materials ◽  
2016 ◽  
Vol 9 (3) ◽  
pp. 199 ◽  
Author(s):  
Yahong Qin ◽  
Tijun Chen ◽  
Yingjun Wang ◽  
Xuezheng Zhang ◽  
Pubo Li
Keyword(s):  
Microstructural Evolution ◽  
Powder Mixture ◽  
Bulk Alloy ◽  
Cold Pressing ◽  
Partial Remelting

Microstructural Evolution of AZ91D-1.5%Er during Semi-Solid Isothermal Treatment

2012 ◽  
Vol 192-193 ◽  
pp. 238-245 ◽  
Author(s):  
Hong Yu Xu ◽  
Ze Sheng Ji ◽  
Zhen Yu Wang
Keyword(s):  
Microstructural Evolution ◽  
Heating Temperature ◽  
Liquid System ◽  
Isothermal Treatment ◽  
Az91d Magnesium Alloy ◽  
Primary Particles ◽  
Recycling Technology ◽  
Paper Chip ◽  
Semi Solid ◽  
Solid Liquid

In this paper, chip recycling technology combined with SIMA method which is called CR-SIMA method was adopted to prepare semi-solid billets. AZ91D magnesium alloy was refined by Er and its microstructural evolution was investigated during semi-solid isothermal treatment. The results show that Er can improve the feature of cast structure and decrease the grain size. Moreover, the γ-Mg17Al12 phase is well refined and disperses in the α-Mg matrix. A semisolid microstructure with small and spheroidal primary particles can be obtained after partially remelting. With increasing heating temperature, the dissolution of eutectic Mg17Al12 phase first took place, resulting in the primary dendritic grains coarsening into interconnected non-dendritic grains. With heating continuously, the residual interdendritic γ-Mg17Al12 at the edges of the primary grains melted in succession and the primary grains separated into small polygon grains. During the semi-solid isothermal treatment, the amount of liquid increased until the solid-liquid system reached its equilibrium state. At the same time, owing to the decreasing of interfacial energy, the grains gradually spheroidized and began to grow with a further increasing of the holding time.

scholarly journals Effects of Partial Remelting on Microstructure of Al-Si-Ti Bulk Alloy Prepared by Cold Pressing Mixed Powders

2016 ◽  
Vol 57 (7) ◽  
pp. 1124-1133 ◽  
Author(s):  
Y.J. Wang ◽  
T.J. Chen ◽  
S.Q. Zhang ◽  
Y.H. Qin ◽  
X.Z. Zhang
Keyword(s):  
Bulk Alloy ◽  
Cold Pressing ◽  
Partial Remelting

scholarly journals Quality and Antioxidant Properties of Cold-Pressed Oil from Blanched and Microwave-Pretreated Pomegranate Seed

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 712
Author(s):  
Tafadzwa Kaseke ◽  
Umezuruike Linus Opara ◽  
Olaniyi Amos Fawole
Keyword(s):  
Radical Scavenging ◽  
Total Phenolic ◽  
Yellowness Index ◽  
Cold Pressing ◽  
Microwave Pretreatment ◽  
Radical Scavenging Capacity ◽  
Scavenging Capacity ◽  
Pomegranate Seed ◽  
Cold Pressed

The present research studied the influence of blanching and microwave pretreatment of seeds on the quality of pomegranate seed oil (PSO) extracted by cold pressing. Pomegranate seeds (cv. Acco) were independently blanched (95 ± 2 °C/3 min) and microwave heated (261 W/102 s) before cold pressing. The quality of the extracted oil was evaluated with respect to oxidation indices, refractive index, yellowness index, total carotenoids content, total phenolic content, flavor compounds, fatty acid composition, and 2.2-diphenyl-1-picryl hydrazyl (DPPH) and 2.2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity. Blanching and microwave pretreatments of seeds before pressing enhanced oil yield, total phenolic content, flavor compounds, and DPPH and ABTS radical scavenging capacity. Although the levels of oxidation indices, including the peroxide value, free fatty acids, acid value, ρ-anisidine value, and total oxidation value, also increased, and the oil quality conformed to the requirements of the Codex Alimentarius Commission (CODEX STAN 19-1981) standard for cold-pressed vegetable oils. On the other hand, blanching and microwave heating of seeds decreased the pomegranate seed oil’s yellowness index, whilst the refractive index was not significantly (p > 0.05) affected. Even though both blanching and microwave pretreatment of seeds added value to the cold-pressed PSO, the oil extracted from blanched seeds exhibited lower oxidation indices. Regarding fatty acids, microwave pretreatment of seeds before cold pressing significantly increased palmitic acid, oleic acid, and linoleic acid, whilst it decreased the level of punicic acid. On the contrary, blanching of seeds did not significantly affect the fatty acid composition of PSO, indicating that the nutritional quality of the oil was not significantly affected. Therefore, blanching of seeds is an appropriate and valuable step that could be incorporated into the mechanical processing of PSO.

scholarly journals Quality of wheat germ oil obtained by cold pressing and supercritical carbon dioxide extraction

2013 ◽  
Vol 31 (No. 3) ◽  
pp. 236-240 ◽  
Author(s):  
M.M. Özcan ◽  
A. Rosa ◽  
M.A. Dessi ◽  
B. Marongıu ◽  
A. Pıras ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Wheat Germ ◽  
Alpha Tocopherol ◽  
Fatty Acid Profiles ◽  
Wheat Germ Oil ◽  
Cold Pressing ◽  
Carbon Dioxide Extraction ◽  
Total Fatty Acids ◽  
Cold Pressed

Laboratory-prepared wheat germ oil was obtained by cold pressing and supercritical CO<sub>2</sub> extraction. The main objective was to compare the quality of both oil samples obtained, with emphasis on their fatty acids compositions and tocopherol contents. The percentages of palmitic, oleic, linoleic, and linolenic acids determined in the cold-pressed oil were 15.89, 15.48, 54.88, and 7.34% of total fatty acids, respectively, and those in the oil extracted by supercritical CO<sub>2</sub> were 16.50, 15.05, 54.79, and 7.29% of total fatty acids, respectively. The average proportions of saturated, mono- and polyunsaturated fatty acids calculated for wheat germ oil obtained by cold pressing accounted for 17.15, 17.63, and 62.22% of total fatty acids, respectively, and those calculated for wheat germ oil extracted by supercritical CO<sub>2</sub> were very similar, accounting for 18.14, 17.58, and 62.08% of total fatty acids, respectively. As expected, the fatty acid profiles determined in both oils studied were observed to be almost identical. In contrast, the level of &alpha;-tocopherol in the oil extracted by supercritical CO<sub>2</sub> was found to be considerably higher (1.27 mg/g) than that in the oil obtained by the cold pressing procedure (0.79 mg/g). &nbsp;

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