Effect of rapid heating and cooling on the transition from transcrystalline to intercrystalline fracture of low-alloy molybdenum alloys

1974 ◽  
Vol 6 (4) ◽  
pp. 452-454
Author(s):  
A. S. Drachinskii ◽  
V. A. Pisarenko ◽  
V. I. Trefilov
Keyword(s):  
Rapid Heating ◽  
Intercrystalline Fracture ◽  
Heating And Cooling ◽  
Molybdenum Alloys

scholarly journals QPOs in compact binaries from small scale eruptions in an inner magnetized disk

2020 ◽  
Author(s):  
Nicolas Scepi ◽  
Mitchell C Begelman ◽  
Jason Dexter
Keyword(s):  
Rapid Heating ◽  
Small Scale ◽  
Type B ◽  
Periodic Oscillations ◽  
X Ray ◽  
Compact Binaries ◽  
Heating And Cooling ◽  
Low Mass ◽  
X Ray Binaries ◽  
Standard Disk

Abstract Dwarf novæ (DNe) and low mass X-ray binaries (LMXBs) are compact binaries showing variability on time scales from years to less than seconds. Here, we focus on explaining part of the rapid fluctuations in DNe, following the framework of recent studies on the monthly eruptions of DNe that use a hybrid disk composed of an outer standard disk and an inner magnetized disk. We show that the ionization instability, that is responsible for the monthly eruptions of DNe, is also able to operate in the inner magnetized disk. Given the low density and the fast accretion time scale of the inner magnetized disk, the ionization instability generates small, rapid heating and cooling fronts propagating back and forth in the inner disk. This leads to quasi-periodic oscillations (QPOs) with a period of the order of 1000 s. A strong prediction of our model is that these QPOs can only develop in quiescence or at the beginning/end of an outburst. We propose that these rapid fluctuations might explain a subclass of already observed QPOs in DNe as well as a, still to observe, subclass of QPOs in LMXBs. We also extrapolate to the possibility that the radiation pressure instability might be related to Type B QPOs in LMXBs.

Rapid heating and cooling of aluminum alloys in a fluidized bed

1970 ◽  
Vol 12 (2) ◽  
pp. 156-159 ◽  
Author(s):  
V. P. Kurbatov ◽  
V. I. Murav'ev
Keyword(s):  
Aluminum Alloys ◽  
Fluidized Bed ◽  
Rapid Heating ◽  
Heating And Cooling

High Productivity Thermo-Compression Flip Chip Bonding

2014 ◽  
Vol 2014 (1) ◽  
pp. 000100-000106
Author(s):  
Tom Colosimo ◽  
Horst Clauberg ◽  
Evan Galipeau ◽  
Matthew B. Wasserman ◽  
Michael Schmidt-Lange ◽  
...  
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Flip Chip ◽  
Solder Joints ◽  
Rapid Heating ◽  
Temperature Cycle ◽  
Temperature Uniformity ◽  
Heating Rates ◽  
Heating And Cooling ◽  
Chip Technology

Advancements in electronic packaging performance and cost have historically been driven by higher integration primarily provided by fab shrinks that has followed the well-known Moore's law. However, due to the tremendous and continuously increasing cost of building new fabs, the performance/cost improvements achieved via node shrinks are negated. This leaves packaging innovation as the vehicle to achieve future cost-performance improvements. This has initiated a More-than-Moore idea that has led to vigorous R&D in packaging. Advanced packages which employ ultra-fine pitch flip chip technology for chip-to-substrate, chip-to-chip, or chip-to-interposer for the first level interconnect have been developed as an answer to obtaining higher performance. However, the costs are too high as compared to traditional wire bonding. The status today is that the fundamental technical hurdles of manufacturing the new advanced packages have been solved, but cost reduction and yield improvements have to be addressed for large-scale adoption into high volume manufacturing. In traditional flip chip assembly silicon chips are tacked onto a substrate and then the solder joints are melted and mass reflowed in an oven. This mass reflow technique is troublesome as the pitch of the solder bumps become finer. This is due to the large differences in the thermal expansion coefficient of the die and the substrate, which creates stress at the solder joints and warpage of the package when the die and substrate are heated and cooled together. To mitigate and resolve this issue, thermo-compression bonders have been developed which locally reflow the solder without subjecting the entire substrate to the heating and cooling cycle. This requires that the bondhead undergo heating past the melting point of solder and then cooling down to a low enough temperature to pick the next die from the wafer that is mounted to tape. Machines in the market today can accomplish this temperature cycle in 7 to 15 seconds. This is substantially slower than the standard flip chip process which leads to high cost and is delaying the introduction of these new packages. This paper shows a flip chip bonder with a new heating and cooling concept that will radically improve the productivity of thermo-compression bonding. Data and productivity cycles from this new bond head with heating rates of over 200°C/sec and cooling of faster than 100°C/sec are revealed. Experimental results are shown of exceptional temperature accuracy across the die of 5°C throughout the cycle and better than 3°C at the final heating stage. The high speed thermo-compression bonds are analyzed and the efficacy of the new concept is proven. Excellent temperature uniformity while heating rapidly is an absolute necessity for enabling good solder joints in a fast process. Without good temperature uniformity, additional dwell times need to be incorporated to allow heat to flow to all of the joints, negating any benefits from rapid heating. Whereas the current state-of-that-art is often to program temperature in steps, this bonder can be commanded and accurately follows more complex temperature profiles with great accuracy. Examples of how this profiling can be used to enhance the uniformity and integrity of the joints with non-conductive pastes, film, and without underfill along with the associated productivity improvements will be shown. Tests that show portability across platforms that will lead to set up time and yield improvements and are identified and quantified. Additionally new ideas for materials and equipment development to further enhance productivity and yield are explored.

Modelling of laser cladding of medium carbon steel - a first approach

2004 ◽  
Vol 120 ◽  
pp. 405-412
Author(s):  
J. Ahlström ◽  
B. Karlsson ◽  
S. Niederhauser
Keyword(s):  
Carbon Steel ◽  
Laser Beam ◽  
Laser Cladding ◽  
Rapid Heating ◽  
Current Model ◽  
Substrate Material ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Heating And Cooling ◽  
Railway Wheels

A model on laser cladding of medium carbon steel, used in railway wheels and rails, is developed and implemented. When the laser beam is scanned over the surface during the cladding operation, phase transformations occur in the topmost layer of the substrate material due to rapid heating and cooling. The hardened regions may later be annealed, either during subsequent passes of the laser beam or by for example induction heating. The current model is a first step towards judging the resulting microstructure and hardness in the heat affected zone under the clad.

Enhanced Wear Resistance of Al-15Si and ZK60-1Y Mg Alloys Induced by High Current Pulsed Electron Beam Treatment

2011 ◽  
Vol 189-193 ◽  
pp. 1204-1207 ◽  
Author(s):  
Bo Gao ◽  
Yi Hao ◽  
Gan Feng Tu ◽  
Shi Wei Li ◽  
Sheng Zhi Hao ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Electron Beam ◽  
Rapid Heating ◽  
Mg Alloys ◽  
Surface Wear ◽  
High Current ◽  
Pulsed Electron Beam ◽  
Heating And Cooling ◽  
Melted Layer ◽  
Modification Of Materials

High current pulsed electron beam (HCPEB), a novel high-power energetic beam technology, has been developed as a useful tool for surface modification of materials. In the present work, the effect of HCPEB treatment on microstructure and wear resistance of Al-15Si and ZK60-1Y Mg alloys was investigated. The results show that a supersaturated solid solution of (Al) and (Mg) is formed on top surface of melted layer induced by rapid heating and cooling during HCPEB process. In addition, the melted layer of approximately 5~11μm thickness is obtained on the ZK60-1Y Mg alloy surface. Wear resistance of Al-15Si and ZK60-1Y Mg alloys are significantly improved after HCPEB treatment. It is demonstrated that HCPEB technology has a good application future in enhancing surface properties of Al-Si and Mg alloys.

scholarly journals Interrelation of microstructure and thermodynamic parameters in TiNi alloy during multiple martensitic transformations

2019 ◽  
Vol 298 ◽  
pp. 00002
Author(s):  
Anna Churakova
Keyword(s):  
Thermodynamic Parameters ◽  
Rapid Heating ◽  
Martensitic Transformations ◽  
Coarse Grained ◽  
Tini Alloy ◽  
Thermal Cycles ◽  
Fast Heating ◽  
Heating And Cooling ◽  
Coarse Grained State ◽  
Consistent Increase

The effect of multiple martensitic transformations on the microstructure and thermodynamic parameters of the alloy of the TiNi system was investigated. It was shown that in the Ti50Ni50 alloy, with an increase in the number of thermal cycles with rapid heating and cooling up to n = 100, a consistent increase in the dislocation density occurs, and a decrease in the width of martensitic plates is observed. And also, that in TCs with fast heating and cooling of the Ti50Ni50 alloy in a coarse-grained state, a change in the trend in the temperatures of martensitic transformations is observed — with an increase in the number of thermal cycles to n = 50, they decrease, and at n> 50 the temperatures increase.

PREPARATION, MICROSTRUCTURE AND PERFORMANCE OF NANOSCALE CERAMICS REINFORCED HARD COMPOSITE COATING

2014 ◽  
Vol 21 (01) ◽  
pp. 1450004 ◽  
Author(s):  
PENG LI
Keyword(s):  
Composite Coating ◽  
Laser Cladding ◽  
Sliding Wear ◽  
Rapid Heating ◽  
Dry Sliding Wear ◽  
Nanoscale Particles ◽  
Heating And Cooling ◽  
And Performance ◽  
First Time ◽  
Microstructure And Performance

This paper is based on the dry sliding wear of Stellite SF 12- B 4 C - TiN - Mo composite coating deposited on a pure Ti using a laser cladding technique, the parameters of which provide almost crack-free composites with low porosity. To the best of our knowledge, it is the first time that Stellite SF 12- B 4 C - TiN - Mo mixed powders are deposited as the hard composites by a laser cladding technique. Scanning electron microscope images indicate that the nanoscale particles are produced in such coating. The fact that due to the sufficiently rapid heating and cooling rates of the laser cladding technique, the ceramics, such as TiC or TiB 2 did not have enough time to grow up, resulting in the formation of the nanoscale particles. Compared with a pure Ti substrate, the increments of the micro-hardness and wear resistance are obtained for such composite coating.

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