Behavior of Cr-Rich Phase during Rapid Solidification Cu71Cr29 Alloys

2011 ◽  
Vol 228-229 ◽  
pp. 101-105
Author(s):  
Zhi Ming Zhou ◽  
Li Wen Tang ◽  
Jing Luo ◽  
Tao Zhou ◽  
Jie Zhan ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
The Other ◽  
Solidification Behavior ◽  
Rich Phase ◽  
Splat Quenching ◽  
The One ◽  
Average Size ◽  
Scanning Electron

Behavior of Cr-rich phase in rapid solidification Cu71Cr29 alloys was investigated by using melt spinning and splat quenching. The microstructure and solidification behavior of the Cr-rich were investigated by scanning electron microscopy (SEM). The results showed that the alloys generally have a microstructure consisting of a fine dispersion of a Cr-rich phase in a Cu-rich matrix. However, the morphology and size of the Cr-rich phase vary greatly with the cooling rate. On the one hand, the average size of the Cr-rich phase is reduced with increasing cooling rate. On the other hand, the Cr-rich phase show both dendrites and spheroids for lower cooling rate but only spheroids for the higher cooling rate. This means liquid phase separation occurred during rapid solidification. The results were discussed with respect to the formation of the Cr-rich spheroids during rapid solidification.

Effect of Cooling Rate on the Microstructure of Cu80Cr20 Alloys

2011 ◽  
Vol 694 ◽  
pp. 704-707
Author(s):  
Z.M. Zhou ◽  
W.J. Huang ◽  
J. Luo ◽  
X.P. Li ◽  
T. Zhou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cooling Rate ◽  
Electromagnetic Levitation ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Rich Phase ◽  
Arc Melting ◽  
Splat Quenching ◽  
Scanning Electron

The effect of cooling rate on the microstructure of Cu80Cr20 alloys was studied by using vacuum non-consumable arc melting, vacuum induction melting, electromagnetic levitation and splat quenching. The microstructure evolution of the Cr-rich were analyzed by scanning electron microscopy (SEM) and optical microscopy. The results showed that nonuniform Cr-rich dendrite distributes on Cu-rich matrix for arc melted alloys and uniform Cr-rich dendrite distributes on Cu-rich matrix for electromagnetic levitation melted alloys and vacuum induction melted alloys. However, the Cr-rich phase show both dendrites and spheroids for splat quenched alloys. This means liquid phase separation occurred during rapid solidification.

Microstructure of Cu75Cr25 Alloys under Different Conditions

2011 ◽  
Vol 230-232 ◽  
pp. 247-250
Author(s):  
Zhi Ming Zhou ◽  
Wei Jiu Huang ◽  
Li Wen Tang ◽  
Xiao Ping Li ◽  
Jing Luo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phase Separation ◽  
Liquid Phase ◽  
Electromagnetic Levitation ◽  
Solidification Behavior ◽  
Rich Phase ◽  
Arc Melting ◽  
Splat Quenching ◽  
Scanning Electron

The microstructure of Cu75Cr25 alloys was investigated by using vacuum non-consumable arc melting, electromagnetic levitation and splat quenching. The microstructure and solidification behavior of the Cr-rich were investigated by scanning electron microscopy (SEM). The results showed that inhomogeneous Cr-rich dendrite distributes on Cu-rich matrix for arc melted alloys. The microstructure consisting of a fine dispersion of Cr-rich dendrite in a Cu-rich matrix for electromagnetic levitated alloys. However, the morphology and size of the Cr-rich phase vary greatly with the cooling rate for splat quenched alloys. The Cr-rich phase show both dendrites and spheroids, this means liquid phase separation occurred during rapid solidification.

Microstructure of Rapidly Solidified CuFe10 Alloys

2010 ◽  
Vol 160-162 ◽  
pp. 687-691
Author(s):  
Zhi Ming Zhou ◽  
Li Wen Tang ◽  
Chun Liu ◽  
Min Min Cao ◽  
Bin Bin Lei
Keyword(s):  
Rapid Solidification ◽  
Melt Spinning ◽  
Supersaturated Solid Solution ◽  
Wide Distribution ◽  
Wheel Speed ◽  
Solidification Behavior ◽  
Wheel Surface ◽  
Rich Phase ◽  
Mean Size ◽  
Rapidly Solidified

Rapid solidification of CuFe10 alloys was carried out by melt spinning at three wheel speeds 4, 12 and 36 m/s. The microstructure and solidification behavior of the ribbons was investigated by scanning electron microscopy (SEM). The results showed that the ribbons generally have a microstructure consisting of a fine dispersion of a Fe-rich phase in a Cu-rich matrix, and that the morphology and size of the Fe-rich phase vary with the wheel speed. For lower wheel speeds, the Fe-rich phase shows dual morphologies, dendrites and spheroids. The Fe-rich spheroids show a wide distribution of size, and have a larger mean size on the free surface than on the wheel surface. Some Fe-rich dendrites are distributed around the Fe-rich spheroids, this means liquid phase separation occurred during rapid solidification. The Fe-rich phase shows one morphology-spheroids and the size of Fe-rich spheroids decreasing as the wheel speed increasing. The results were discussed with respect to the formation of the Fe-rich spheroids during rapid solidification. The microhardness of the ribbons increasing with the increasing of the wheel speed for the grain refining and the increasing of supersaturated solid solution.

scholarly journals Nucleation Behavior of a Single Al-20Si Particle Rapidly Solidified in a Fast Scanning Calorimeter

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2920
Author(s):  
Qin Peng ◽  
Bin Yang ◽  
Benjamin Milkereit ◽  
Dongmei Liu ◽  
Armin Springer ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Rapid Solidification ◽  
Heterogeneous Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Solidification Behavior ◽  
Nucleation Kinetics ◽  
Nucleation Behavior ◽  
Nucleation Undercooling ◽  
Primary Si

Understanding the rapid solidification behavior characteristics, nucleation undercooling, and nucleation mechanism is important for modifying the microstructures and properties of metal alloys. In order to investigate the rapid solidification behavior in-situ, accurate measurements of nucleation undercooling and cooling rate are required in most rapid solidification processes, e.g., in additive manufacturing (AM). In this study, differential fast scanning calorimetry (DFSC) was applied to investigate the nucleation kinetics in a single micro-sized Al-20Si (mass%) particle under a controlled cooling rate of 5000 K/s. The nucleation rates of primary Si and secondary α-Al phases were calculated by a statistical analysis of 300 identical melting/solidification experiments. Applying a model based on the classical nucleation theory (CNT) together with available thermodynamic data, two different heterogeneous nucleation mechanisms of primary Si and secondary α-Al were proposed, i.e., surface heterogeneous nucleation for primary Si and interface heterogenous nucleation for secondary α-Al. The present study introduces a practical method for a detailed investigation of rapid solidification behavior of metal particles to distinguish surface and interface nucleation.

Assortment Size and PL Penetration in Grocery Retailers' Portfolios during Economic Crisis

2016 ◽  
pp. 244-274 ◽  
Author(s):  
José Luis Ruiz-Real ◽  
Juan Carlos Gázquez-Abad ◽  
Francisco J. Martínez-López
Keyword(s):  
Economic Crisis ◽  
The Other ◽  
Product Categories ◽  
Other Hand ◽  
Competitive Prices ◽  
The One ◽  
Average Size ◽  
Buying Behaviour ◽  
Retail Formats

The economic crisis in Spain has had a major impact on the evolution of retail assortments in food base. On the one hand, it has caused alterations in assorted sizes, as well as in the distribution between NB and PL. On the other hand, it has changed the buying behaviour of consumers seeking brands that offer confidence, but at very competitive prices. The purpose of this chapter is to answer the following questions: How has the economic crisis changed the assortment size in different categories of products in Spanish groceries? In which way has the assortment composition of retailers been altered? Do all the retail formats have the same behaviour in assortment management and PL? The authors argue that there has been an increase in the average size of assortment for all the product categories with the exception of products of fill-ins, and the only two retail formats that have increased the weight of the PL in their assortments are large and medium-sized supermarkets.

Some Fundamental Considerations During Rapid Solidification Processing

1983 ◽  
Vol 28 ◽  
Author(s):  
V. Laxmanan
Keyword(s):  
Cooling Rate ◽  
Rapid Solidification ◽  
Stability Criterion ◽  
Thermal Gradient ◽  
Absolute Stability ◽  
Melt Spinning ◽  
Rapid Solidification Processing ◽  
Dendritic Solidification ◽  
Solidification Processing ◽  
The Third

ABSTRACTThree estimates of the solidification rates required to obtain a fully homogeneous structure during rapid solidification processing (RSP) have been made. One is given by the “absolute stability” criterion and another obtained from a new analysis for dendritic solidification. The third estimate, also derived from the above analysis, requires that “hypercooled” conditions be maintained after nucleation. A mechanism for the formation of “featureless” segregation-free zones during melt spinning and atomization processes is suggested and expressions for the critical cooling rate and thermal gradient required to produce such structures have been obtained.

Effect of Cooling Rate on Structural and Chemical Microheterogeneity of IN 738LC Nickel Based Superalloy

2008 ◽  
Vol 138 ◽  
pp. 201-208 ◽  
Author(s):  
Jana Dobrovská ◽  
Simona Dočekalová ◽  
Věra Dobrovská ◽  
Karel Stránský
Keyword(s):  
Cooling Rate ◽  
Experimental System ◽  
Solidification Behavior ◽  
Ramp Rate ◽  
Concentration Data ◽  
Measured Concentration ◽  
X Ray ◽  
Nickel Based Superalloy ◽  
The Individual ◽  
Scanning Electron

The paper deals with the effect of cooling rate on solidification behavior of IN 738LC nickel based superalloy and on resulting structural and chemical microheterogeneity of this alloy. Samples taken from as-received state were heated with controlled ramp rates (1, 5, 10 and 20 °C min-1). Immediately after melting they were cooled with the same controlled ramp rate with the help of the laboratory experimental system SETARAM SETSYS 18TM TG/DTA/TMA. Then the microanalysis of minority phases was conducted with use of X-ray spectroscopy and microstructure of the individual samples was documented by scanning electron microscopy. Chemical microheterogeneity was determined on the basis of measured concentration data of selected elements (Al, Ti, Cr, Co, Ni, Nb, Mo, Ta and W) in representative areas of the individual samples structure.

scholarly journals Productivity in Small Business: An Analysis Using African Data

1986 ◽  
Vol 11 (1) ◽  
pp. 27-42 ◽  
Author(s):  
A. Roy Thurik
Keyword(s):  
Small Business ◽  
South African ◽  
Support System ◽  
The Other ◽  
Cost Functions ◽  
Average Volume ◽  
Service Business ◽  
Business Support ◽  
The One ◽  
Average Size

Labor and floorspace cost functions are derived for small business trade. Relationships are proposed between average volume of labor or average floorspace per establishment on the one hand, and average size per establishment, average rental paid, percentage selling space, and indicators of business type and location on the other. Promising estimation results are reported using South African data of 1979/1980. The method however Is not restricted to the South African case. A productivity business support system can be developed providing productivity standards for any area in the small (service) business. An analysis similar to the one presented here, but relating to the area in question, should precede the development of such a system.

Feeding relationships between sympatric Afrotropical tree frogs (genus Hyperolius): The effects of predator body size and season

2004 ◽  
Vol 54 (3) ◽  
pp. 293-302 ◽  
Author(s):  
◽  
◽  
◽  
◽  
◽  
...  
Keyword(s):  
Interspecific Competition ◽  
Diet Composition ◽  
Sexual Size Dimorphism ◽  
Stomach Contents ◽  
The Other ◽  
Size Dimorphism ◽  
Frog Species ◽  
Tree Frogs ◽  
The One ◽  
Average Size

AbstractThe feeding relationships of four sympatric, ecologically nearly unknown, tree frogs of southern Nigeria (Hyperolius sylvaticus, H. guttulatus, H. fusciventris burtoni, and H. concolor) were studied during both the dry and the rainy seasons. Stomach contents were obtained by stomach flushing. The largest species were H. guttulatus and H. concolor, whereas the other two species were of smaller average size. A statistically significant sexual size dimorphism was observed in H. guttulatus, H. concolor, and H. sylvaticus (in all species the females were larger), but not in H. fusciventris. In all four species, the frequency of animals with empty stomachs was significantly lower during the rainy season than during the dry season. The four frog species were mainly arthropodeating: Araneidae and Blattoidea were preyed upon mainly by the two largest species, Acarina and Lepidoptera were taken mainly by the two smaller species, and Diptera and Formicoidea were eaten frequently by all species. The diet composition was similar between seasons in three of the four species, and H. guttulatus was the only species showing considerable diet variation between seasons. We concluded that 1) the intensity of interspecific competition should be particularly high between the two larger species on the one hand, and between the two smaller species on the other hand; and 2) the intensity of the interspecific competition should be relatively constant throughout the year.

Effects of the Cooling Rate on the Solidification Microstructure of Cu-Ni Alloy

2010 ◽  
Vol 658 ◽  
pp. 444-447
Author(s):  
Jia Wei Yuan ◽  
Yu Hua Pang ◽  
Yang Lei Hu ◽  
Qi Sun ◽  
Dong Liu ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Low Carbon Steel ◽  
Solidification Process ◽  
Simulation Software ◽  
Solidification Microstructure ◽  
Silica Sand ◽  
Low Carbon ◽  
Ni Alloy ◽  
Average Size ◽  
Scanning Electron

The effect of cooling rate on the solidification microstructure of Cu-Ni alloy is investigated here. The Cu-Ni alloy was prepared in a main frequency furnace with three different molds made of silica sand, graphite, and low carbon steel in the foundry. The simulation software of diathermanous-flowing-stress coupling PROCAST is used to simulate the Cu-Ni alloy solidification process about temperature field with the three molds. The microstructures of the alloys have been studied through the optical microscopy (OM), the scanning electron microscopy (SEM), together with the energy dispersive spectroscopy (EDS).The results show that the grain average size and the primary and secondary dendrite arm space were obviously reduced with the increase of cooling rate. The dendrite and interdendrite element segregation also decreases with increasing cooling rate.

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