Measurement of Phase Boundary Dynamics During Scanned Laser Crystallization of Amorphous Ge Films

1980 ◽  
Vol 1 ◽  
Author(s):  
R. L. Chapman ◽  
John C. C. Fan ◽  
H. J. Zeiger ◽  
R. P. Gale
Keyword(s):  
Laser Scanning ◽  
Structural Features ◽  
Fused Silica ◽  
Beam Power ◽  
Laser Crystallization ◽  
Transmission Method ◽  
Laser Beam Power ◽  
Boundary Velocity ◽  
Background Temperature ◽  
Boundary Dynamics

ABSTRACTTwo techniques have been used to measure the velocity of the amorphous-crystalline boundary during scanned laser crystallization of amorphous Ge films on fused-silica substrates. Values in the vicinity of 200 cm sec-1 have been measured by both methods. The results obtained by the first technique, an optical transmission method, confirm our theoretical model for the periodic motion of the boundary. The measurements made by the second technique, which is based on an examination of the structural features obtained at laser scanning rates up to about 600 cm sec-1 , show the boundary velocity to be rather insensitive to film thickness and background temperature. Controlled crystallization is expected to require stability of the laser beam power.

scholarly journals Characteristics of Cr-B Coatings Produced on Vanadis® 6 Tool Steel Using Laser Processing

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2621
Author(s):  
Aneta Bartkowska
Keyword(s):  
Corrosion Resistance ◽  
Tool Steel ◽  
Laser Processing ◽  
Chemical Elements ◽  
Steel Substrate ◽  
Processing Parameters ◽  
Beam Power ◽  
Laser Beam Power ◽  
High Microhardness ◽  
The Impact

The paper presents the results of a study of the microstructure, chemical composition, microhardness and corrosion resistance of Cr-B coatings produced on Vanadis 6 tool steel. In this study, chromium and boron were added to the steel surface using a laser alloying process. The main purpose of the study was to determine the impact of those chemical elements on surface properties. Chromium and boron as well as their mixtures were prepared in various proportions and then were applied on steel substrate in the form of precoat of 100 µm thickness. Depending on the type of precoat used and laser processing parameters, changes in microstructure and properties were observed. Coatings produced using precoat containing chromium and boron mixture were characterized by high microhardness (900 HV0.05–1300 HV0.005) while maintaining good corrosion resistance. It was also found that too low laser beam power contributed to the formation of cracks and porosity.

scholarly journals The influence of laser re-melting on microstructure and hardness of gas-nitrided steel

2016 ◽  
Vol 36 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Dominika Panfil ◽  
Piotr Wach ◽  
Michał Kulka ◽  
Jerzy Michalski
Keyword(s):  
Laser Beam ◽  
Laser Treatment ◽  
Diffusion Zone ◽  
Nitrided Layer ◽  
Nitriding Process ◽  
Beam Power ◽  
Gas Nitriding ◽  
Nitrided Steel ◽  
Laser Beam Power ◽  
And Diffusion

Abstract In this paper, modification of nitrided layer by laser re-melting was presented. The nitriding process has many advantageous properties. Controlled gas nitriding was carried out on 42CrMo4 steel. As a consequence of this process, ε+γ’ compound zone and diffusion zone were produced at the surface. Next, the nitrided layer was laser remelted using TRUMPF TLF 2600 Turbo CO2 laser. Laser tracks were arranged as single tracks with the use of various laser beam powers (P), ranging from 0.39 to 1.04 kW. The effects of laser beam power on the microstructure, dimensions of laser tracks and hardness profiles were analyzed. Laser treatment caused the decomposition of continuous compound zone at the surface and an increase in hardness of previously nitrided layer because of the appearance of martensite in re-melted and heat-affected zones

Laser Welding Influence on Corrosion Rate of Galvanized Sheets of DP600 Automobilistic Alloy

2020 ◽  
Vol 1012 ◽  
pp. 436-440
Author(s):  
Viviane Teleginski Mazur ◽  
Sílvia Rosa Nascimento ◽  
Marilei de Fátima Oliveira ◽  
Willer Cézar Braz ◽  
Correard Gilson Carlos de Castro ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Open Circuit Potential ◽  
Scanning Speed ◽  
Open Circuit ◽  
Galvanized Steel ◽  
Beam Power ◽  
Laser Weld ◽  
Corrosion Studies ◽  
Laser Beam Power ◽  
Rate Behavior

Corrosion rate behavior of laser welded dual-phase galvanized steel, DP 600, has been assessed in comparison with the material without the laser weld, in 3.5% NaCl solution. Three combinations of both scanning speed and laser power parameters were selected, maintaining the thermal input of 30 J mm-1, calculated as the ratio between the laser beam power [W] and the scanning speed [mm s-1]. The corrosion studies included measurements of open circuit potential, micro and macro polarization, showing higher corrosion rates as scanning speed decreased. Optical microscopy showed the formation of a grain size refined morphology in the heat affected zone and fusion zone. A mechanism has been proposed to explain the corrosion behavior as a function of the laser parameters, which dictated the galvanized coating vaporization.

Laser beam power fade induced by system and atmospheric effects

1982 ◽  
Vol 21 (13) ◽  
pp. 2432 ◽  
Author(s):  
U. Halavee ◽  
M. Tamir ◽  
E. Azoulay
Keyword(s):  
Laser Beam ◽  
Beam Power ◽  
Atmospheric Effects ◽  
Laser Beam Power ◽  
Power Fade

Relationship between Laser Parameters - Microstructural Modification - Mechanical Properties of Laser Surface Melted Magnesium Alloy AZ91D

2013 ◽  
Vol 765 ◽  
pp. 678-682
Author(s):  
Catalina Taltavull ◽  
Belen Torres ◽  
Antonio Julio Lopez ◽  
Joaquin Rams
Keyword(s):  
Mechanical Properties ◽  
Surface Treatment ◽  
Laser Scanning ◽  
High Energy ◽  
Surface Melting ◽  
Laser Surface ◽  
Laser Surface Melting ◽  
Beam Power ◽  
Laser Parameters ◽  
Alloy Az91d

Laser surface melting is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys. In the present work, a high-power diode laser has been used to study the microstructural and mechanical modifications that occur when laser surface treatments are applied to the surface of the AZ91D Mg alloy. Laser-beam power in a range of 375-600 W and laser scanning speeds of 45-60-90 mms-1 has been used to develop a range of laser surface melting treatments. By controlling the laser parameters, two types of surface modifications can be obtained. Complete laser surface melting takes place at high laser input energies whilst at low laser input energies, selective laser surface melting occurs with modification of only one phase in the microstructure of the alloy; the other phase remained unaffected. In terms of mechanical properties, the microstructural modifications introduced by the laser surface treatment implied a hardness homogenization along the melted region.

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