strengthening phase
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2021 ◽  
pp. 131275
Author(s):  
Baorong Sun ◽  
Long Zheng ◽  
Ping Li ◽  
Guoan Sheng ◽  
Xingong Li ◽  
...  

2021 ◽  
Vol 13 (15) ◽  
pp. 8373
Author(s):  
Isaac Zúniga Aguilar

This article focuses on analyzing the neuroeconomic decisions in cocoa producers and the impact of this methodology on the productivity of fair trade organic cocoa producers on the population of Nuevo Bambamarca, province of Tocache, Peru. The main elements of the methodology are the incentive phase of associativity, the alignment phase to macro trends, the prospecting phase of the country to be exported to, the prospecting phase of the type of niche market, the prospecting phase of fair participation, the innovation and design phase of the prototype, the standardization phase of the raw material technical specifications for collection, the strengthening phase the producer’s commitment, the learning phase of the producer in crop management, and the evaluation phase of productivity in the field. This research study is pre-experimental, cross-sectional, explanatory, and descriptive. The experimental group made up of 20 fair trade organic cocoa producers of the Cooperativa Agroindustrial Naranjillo obtained on average a profitability of 143 EUR per campaign higher than the control group made up of 20 producers of conventional cocoa that did not belong to the cooperative who obtained a loss of −642 EUR per campaign, even with the same purchase price of 1.92 EUR per kg for both cases during the 2011 campaign. It is concluded that Hypothesis 1 is met, it shows that the cooperative innovation methodology of prospecting for fair trade organic niche encourages the productivity of producers of the experimental group with respect to the control group.


Author(s):  
Dengkui Zhang ◽  
Aiping Wu ◽  
Yue Zhao ◽  
Jiguo Shan ◽  
Zhandong Wan ◽  
...  

The effects of Al–Mg wire replacing Al–Cu wire on the microstructure, microhardness and tensile properties of 2219 aluminum alloy tungsten inert gas (TIG)-welded joints were studied. Comparing joints with Al–Cu wire, the capping welds of joints with Al–Mg wire can be strengthened by the introduction of Mg-containing strengthening phase and the hardness can be significantly improved. However, for joints with Al–Mg wire, both the solidification cracks caused by inappropriate control of alloying element content and the continuous brittle phases at grain boundaries around the weld zone (WZ) can result in the reduced tensile properties. The crack-free weld can be obtained by adjusting the alloying system of WZ. Furthermore, the geometry of WZ also affected the tensile properties of joints with Al–Mg wire.


2021 ◽  
Vol 1035 ◽  
pp. 344-349
Author(s):  
Ye Qin Zhang ◽  
Ping Zhong ◽  
Huan Feng Li ◽  
Wen Qiang Zhang

The effect of solution temperature and aging temperature on mechanical properties and microstructure of the new ultrahigh strength stainless steel S280 was investigated by heat treatment process experiment. The results showed that the optimal heat treatment process was as follows: heating to 1080 °C,holding for a hour, and quenching in oil; cooling to -73 °C, holding for 2 hour, and warming in air to room temperature; heating to 540~550 °C, holding for 4 hour, and cooling in air. Choosing this heat treatment process, the steel can get good coordination between strength and toughness. Analyzed by HREM, the steel had desirable microstructures, which were fine lath martensite matrix with high density dislocation and finely dispersed precipitate strengthening phase, and film-like reversed austenite precipitated from the boundary of martensite.


2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Neng Li ◽  
Wei Liu ◽  
Yan Wang ◽  
Zijun Zhao ◽  
Taiqi Yan ◽  
...  

AbstractImportant progresses in the study of laser additive manufacturing on metal matrix composites (MMCs) have been made. Recent efforts and advances in additive manufacturing on 5 types of MMCs are presented and reviewed. The main focus is on the material design, the combination of reinforcement and the metal matrix, the synthesis principle during the manufacturing process, and the resulted microstructures as well as properties. Thereafter, the trend of development in future is forecasted, including: Formation mechanism and reinforcement principle of strengthening phase; Material and process design to actively achieve expected performance; Innovative structure design based on the special properties of laser AM MMCs; Simulation, monitoring and optimization in the process of laser AM MMCs.


2021 ◽  
Vol 1026 ◽  
pp. 74-83
Author(s):  
Guan Jun Gao ◽  
Xi Wu Li ◽  
Li Zhen Yan

Pre-strain (PS) and pre-aging (PA) treatments are often applied during the preparation of Al-Mg-Si automotive aluminum alloy. In this study, the effect of combined PS and PA on the precipitation behavior and age hardening response for Al-Mg-Si alloys was investigated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), tensile test, Vickers hardness test, and differential scanning calorimetry (DSC). It was found that the dislocations introduced by PS treatment and the cluster (2) formed during PA treatment effectively inhibited the cluster (1), which further strengthened the inhibition of natural aging hardening at room temperature (RT). The strength increment of the alloys was kept below 10.0 MPa during two weeks RT storage. The dislocations provided heterogeneous nucleation for the precipitates forming and the cluster (2) transformed into β″ strengthening phase during bake hardening treatment. With the acceleration response of the dislocations and the cluster (2), the age hardening response of Al-Mg-Si alloys obviously improved with the denser and larger β″ strengthening phase formed.


2021 ◽  
Vol 5 ◽  
pp. 18-27
Author(s):  
A. A. Selivanov ◽  
◽  
K. V. Antipov ◽  
Yu. S. Oglodkova ◽  
A. S. Rudchenko ◽  
...  

The results of the development of a new alloy of the Al – Mg – Si system of the 6xxx series, which received the V-1381 grade, are presented. The influence of the composition and modes of heat treatment on the mechanical and corrosion properties of sheets with a thickness of 1,0 and 3,0 mm, manufactured under the conditions of FSUE “VIAM”, was investigated. Average level of sheet properties: UTS = 410 MPa, YTS = 360 MPa, El = 11.5 %; fatigue crack growth (dl/dN) = 0,59 mm/kcycle at ΔK = 18,6 MPa·m1/2, intergranular corrosion ≤ 0,15 mm, exfoliation corrosion 4 points. It was found that the structure of the sheets is recrystallized, the main strengthening phase is the coherent matrix β’(Mg2Si)-phase evenly distributed in the volume of grains with a high density. There is also a heterogeneous origin of β′-phase on dislocations and dispersoids. At grain boundaries there are zones free from emissions with a width of 15 – 20 nm. Dispersoids of various morphologies are observed in the tested samples. Temperature and heat values of phase transformations in ingots and sheets are determined and established liquidus and solidus points. The sheet weldability was evaluated by automatic argon-arc welding and the critical rate of deformation of the weld metal during crystallization was determined, at which no cracks were formed in it. Laser welding mode has been developed to ensure optimal formation of geometric parameters of the weld.


Author(s):  
O.M Dubovoy ◽  
A.A Karpechenko ◽  
M.M Bobrov ◽  
O.S Gerasin ◽  
O.O Lymar

Purpose. Substantiation of the possibility of obtaining composite cermet electric arc coatings using TiC powder as a strengthening phase, determination of their physical and mechanical properties. Methodology. The microstructure of the composite cermet electric arc coatings was studied by computer metallography using a ZEISS Gemini SEM 500 scanning electron microscope. The chemical composition was determined by X-ray spectral analysis; phases were identified by measuring their microhardness on a PMT-3 device. The bond strength of the obtained coatings was determined by the method of pulling out the pintle on a tensile testing machine UMM-5. Findings. Composite cermet coatings of the steel 65G-TiC system were obtained by the electric arc spraying using TiC powder in a free state. The influence of the technological parameters of spraying on the amount of the carbide phase in the coating was established, and their microstructure was investigated. The porosity, microhardness of the phases in the coating and its bond strength were determined. Originality. For the first time, composite cermet electric arc coatings of the steel 65G-TiC system were obtained by using a powder of strengthening phase in a free state. Their microstructure, microhardness and bond strength were investigated. The technological spraying modes of electric arc coatings have been established, which provide the optimal content of the strengthening phase to achieve their maximum bond strength with substrate. Practical value. The application of the research results obtained in the work, namely, the determination of the optimal technological parameters of spraying for the formation of cermet electric arc coatings with the maximum level of physical, mechanical and operational properties, makes it possible to meet the requirements for the restoration and hardening of worn surfaces. This leads to an increase in the service life of parts not only in mining, but also in other industries.


2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Maisaa N. Tawfeeq ◽  
Robert J. Klassen

Abstract Nickel and Helium ion implantation-induced hardening and microstructural evolution of X750 in the heat-treated (HT) and solution annealed (SA) conditions were investigated using nano-indentation hardness testing and electron microscopy (scanning electron microscopy (SEM) and transmission electron microscopy (TEM)). Irradiation crystal damage up to ψ = 5 dpa was invoked with Ni+ implantation while He+ implantation up to CHe = 5000 appm was performed on samples the HT and SA conditions. The X750 alloy displayed generally increasing hardness with increasing Ni+ implantation damage but a perturbation in the trend occurred when ψ ≤ 0.5 dpa, and the hardness dropped by about 30% and 2% for the HT and the SA samples, respectively. TEM analysis indicated that this softening was associated with disordering and dissolution of the γ′ strengthening phase. The hardening behavior observed at higher implantation damage (ψ = 1 dpa) resulted in reformation of Al/Ti-rich regions within the microstructure phase. The hardness of the X750 increased continuously with increasing implanted He+ up to CHe = 1000 appm. This was associated with the formation of helium bubbles as observed by TEM. Slight drop in hardness in the HT condition at CHe = 5000 appm indicated that high levels of He+ implantation destabilize the γ′ precipitates as was confirmed with TEM observed disappearance of γ′ super-lattice reflections.


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