Study on the effects of the compression ratio and mushy zone heating on the thixotropic microstructure of AA 7075 aluminum alloy via SIMA process

The effects of compression ratios on the microstructure evolution of semisolid Al7075 alloy produced by the strain induced melt activation (SIMA) process were investigated. The samples were cold deformed by compression into the different heights up to 40% reduction. The isothermal holding treatments within mushy zone of the alloy were carried out at 610, 620 and 625 °C for predetermined time intervals. The results revealed that the average grain size gradually reduced with the increase in the compressive ratio. While the compressive ratio surpassed 30%, the descending trend above was not as evident as that of below 30% reduction. The optimum condition presenting the minimum grain size and the maximum shape factor with the highest uniformity is discussed. During the subsequent mushy zone heating, the recrystallization was induced in the deformed samples by the increasingly accumulated strain energy. © 2010 Elsevier B.V. All rights reserved

Effects of Pin Design on Materials Interactions to Friction Stir Spot Joining Aluminium Alloys to Carbon Fibre Reinforced Plastics

No abstract available

Coarsening of equiaxed microstructure in the semisolid state of aluminum 7075 alloy through SIMA processing

In the present study, the coarsening mechanism of equiaxed grains in the semisolid state of aluminum 7075 alloy, treated via strain induced melting activation process, was investigated. The kinetics of equiaxed grain growth in the semisolid state of the experimental alloy was determined. The results revealed that when the holding temperature increased, the coarsening rate constant (K) showed a precipitously increasing character in the range of 590-610 °C. This was attributed to the extensive effect of the coalescence mechanism on the grain growth at the high solid fractions. By further increasing the holding temperature to 620 and 625 °C (increasing the liquid fraction), the effect of coalescence on the grain growth appeared to be weakened, that is, although there was a slight decrease at 620 °C, a gently increasing character could be generally supposed. Severe segregation of Zn and Cu alloying elements at grain boundaries and intragranular droplets was detected at 620 and 625 °C after 15 and 10 min, respectively. © 2011 Springer Science+Business Media, LLC

Effects of Pin Design on Materials Interactions to Friction Stir Spot Joining Aluminium Alloys to Carbon Fibre Reinforced Plastics

No abstract available

Sugars and plant innate immunity

Sugars are involved in many metabolic and signaling pathways in plants. Sugar signals may also contribute to immune responses against pathogens and probably function as priming molecules leading to PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI) in plants. These putative roles also greatly depend on coordinated relationships with hormones and the light status in an intricate network. Although evidences in favor of sugar-mediated plant immunity are accumulating, more in-depth fundamental research is required to unravel the sugar signaling pathways involved. This might pave the way to use biodegradable sugar-(like) compounds to counteract plant diseases, as cheaper and safer alternatives for toxic agrochemicals.status: publishe

Polyether Sulfone Interleaved Glass/Carbon Hybrid Composite Under Impact Loading

No abstract available

Spatial variability analysis of subsurface soil in Mashhad city, NE Iran

Reliable characterization of subsurface soil in urban areas is a major concern in geotechnical and geological engineering projects. In this regard, this research deals with development of a 3D geological engineering model on Mashhad City soil using Sequential Gaussian Simulation (SGS) approach. The intense variability of soil in the study area has sometimes caused serious problems in civil engineering projects in the city. Therefore, a better understanding of these deposits is critical for current and future civil engineering work. The main objectives of this study were investigating the spatial variability of soil through variograms and then predicting the values of soil properties at unsampled locations using SGS method. In this study, some geotechnical index parameters including percentage of fine grained material, plasticity index, and liquid limit have been employed as input data. A database including the data of 1750 boreholes was built and the hard data were transformed into normal scores in order for them to be applicable as input data in SGS modeling. Maps related to the average of all realizations along with Coefficient of Variation (CV) were provided for each variable as well. Then the maps were interpreted according to Mashhad City sedimentary environment