The fatigue behavior of fine grained two-phase alloys

1973 ◽  
Vol 4 (2) ◽  
pp. 561-568 ◽  
Author(s):  
H. W. Hayden ◽  
S. Floreen
Keyword(s):  
Fatigue Behavior ◽  
Two Phase ◽  
Fine Grained

Investigation of low- and high-resistance Ni–Ge–Au ohmic contacts to n+ GaAs using electron microbeam and surface analytical techniques

1996 ◽  
Vol 11 (5) ◽  
pp. 1244-1254 ◽  
Author(s):  
Nancy E. Lumpkin ◽  
Gregory R. Lumpkin ◽  
K. S. A. Butcher
Keyword(s):  
Electron Microscopy ◽  
Ohmic Contacts ◽  
Analytical Electron Microscopy ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Two Phase ◽  
Low Resistance ◽  
Fine Grained ◽  
Multiphase Microstructure ◽  
Transmission Electron

A process for the formation of low-resistance Ni–Ge–Au ohmic contacts to n+ GaAs has been refined using multivariable screening and response surface experiments. Samples from the refined, low-resistance process (which measure 0.05 ± 0.02 Ω · mm) and the unrefined, higher resistance process (0.17 ± 0.02 Ω · mm) were characterized using analytical electron microscopy (AEM), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and x-ray photoemission spectroscopy (XPS) depth profiling methods. This approach was used to identify microstructural differences and compare them with electrical resistance measurements. Analytical results of the unrefined ohmic process sample reveal a heterogeneous, multiphase microstructure with a rough alloy-GaAs interface. The sample from the refined ohmic process exhibits an alloy which is homogeneous, smooth, and has a fine-grained microstructure with two uniformly distributed phases. XPS analysis for the refined ohmic process sample indicates that the Ge content is relatively depleted in the alloy (relative to the deposited Ge amount) and enriched in the GaAs. This is not evidenced in the unrefined ohmic process sample. Our data lead us to conclude that a smooth, uniform, two-phase microstructure, coupled with a shift in Ge content from the post-alloy metal to the GaAs, is important in forming low-resistance ohmic contacts.

Development of Superplastic Properties in Quasi Single Phase Alloys

2007 ◽  
Vol 551-552 ◽  
pp. 357-364 ◽  
Author(s):  
Roger Grimes ◽  
R.J. Dashwood ◽  
A. Dorban ◽  
M. Jackson ◽  
S. Katsas ◽  
...  
Keyword(s):  
Single Phase ◽  
Early Stage ◽  
Strip Casting ◽  
Grain Structure ◽  
Freezing Range ◽  
Two Phase ◽  
Fine Grained ◽  
Cast Doubt ◽  
Recent Developments ◽  
Superplastic Properties

The early view of superplasticity was that it was a phenomenon that could only be exhibited by fine grained, two phase alloys. This effectively ruled out most alloys that possessed attractive service properties. The first material to demonstrate good superplastic properties from a virtually single phase microstructure was the Al-6%Cu-0.5%Zr, AA 2004 but this was followed by superplastic versions of AA7475, AA8090 and AA5083. Superplasticity was also demonstrated in magnesium based alloys at an early stage. More recently different grain control additions, such as scandium or erbium have been investigated and it has also been demonstrated that, in certain circumstances, aluminium simply with the addition of a grain controlling element can exhibit good superplastic behaviour. While conventional wisdom teaches that large fabricating strains are required to confer good superplastic properties in the sheet product, recent results with both aluminium and magnesium alloys cast doubt on this belief. Although, for many years, strip casting has appeared to provide an attractive semi-fabricating route for superplastic sheet problems with centre line segregation in alloys with a wide freezing range have precluded its use. It has been demonstrated that recent developments in strip casting enable production of alloys with as wide a freezing range as AA5182 to be cast with a fine, equiaxed grain structure across the strip thickness. The paper will review the state of these various developments and their implications for the manufacture of superplastic sheet materials.

scholarly journals Creep of a fine-grained, fully-lamellar, two-phase TiAl alloy at 760{degree}C

10.2172/46701 ◽  
1995 ◽  
Author(s):  
J.N. Wang ◽  
A.J. Schwartz ◽  
T.G. Nieh ◽  
C.T. Liu ◽  
V.K. Sikka ◽  
...  
Keyword(s):  
Tial Alloy ◽  
Two Phase ◽  
Fine Grained ◽  
Fully Lamellar

scholarly journals Effect of Radial Forging on the Microstructure and Mechanical Properties of Ti-Based Alloys

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1488
Author(s):  
Lev B. Zuev ◽  
Galina V. Shlyakhova ◽  
Svetlana A. Barannikova
Keyword(s):  
Phase State ◽  
Metal Flow ◽  
Mechanical Processing ◽  
Radial Forging ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Fine Grained ◽  
Fine Grained Structure

Radial forging is a reliable way to produce Ti alloy rods without preliminary mechanical processing of their surface, which is in turn a mandatory procedure during almost each stage of the existing technology. In the present research, hot pressing and radial forging (RF) of the titanium-based Ti-3.3Al-5Mo-5V alloy were carried out to study the specifics of plasticized metal flow and microstructural evolution in different sections of the rods. The structural analysis of these rods was performed using metallography and X-ray diffraction techniques. The X-ray diffraction reveals the two-phase state of the alloy. The phase content in the alloy was shown to vary upon radial forging. Finally, radial forging was found to be a reliable method to achieve the uniform fine-grained structure and high quality of the rod surface.

Fatigue Behavior of Ultra-Fine Grained Ti-6Al-4V Alloy

2014 ◽  
pp. 33-51
Author(s):  
R. Ebara ◽  
M. Endo ◽  
H. J. Kim ◽  
J. Nakahigashi
Keyword(s):  
Fatigue Behavior ◽  
Fine Grained

scholarly journals The influence of metallurgical factors on low cycle fatigue behavior of ultra-fine grained 6082 Al alloy

2018 ◽  
Vol 110 ◽  
pp. 130-143 ◽  
Author(s):  
N. Kumar ◽  
S. Goel ◽  
R. Jayaganthan ◽  
G.M. Owolabi
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Al Alloy ◽  
Cycle Fatigue ◽  
Fine Grained ◽  
6082 Al Alloy

Hybrid Design Concept Using High-Strength Cast Steel Inserts for Tubular Joints of Offshore Structures

1998 ◽  
Vol 120 (1) ◽  
pp. 10-19 ◽  
Author(s):  
C. M. Sonsino ◽  
R. Umbach
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Large Scale ◽  
Fatigue Behavior ◽  
Cast Steel ◽  
High Strength ◽  
Offshore Structures ◽  
Fine Grained ◽  
Tubular Joints ◽  
Medium Strength

In a joint project of a German working group supported by the ECSC and the Studiengesellschaft fu¨r Stahlanwendung e.V., the fatigue behavior of large-scale hybrid tubular joints with inserts manufactured from the high-strength cast steel GS-12 MnMo 7 4 welded into tubular members formed from the fine-grained steel StE 500 were compared to the behavior of large-scale welded tubular joints. The latter were made from medium-strength fine-grained steel StE 355 and high-strength StE 690. In addition, data from hybrid joints with cast steel inserts of medium-strength GS-8 Mn 7 welded into StE 355 tubulars is available for comparison. The tests were carried out under variable amplitude loading in artificial seawater. The results were evaluated for the failure criteria fatigue life to crack initiation (a = 1 mm) and through crack. With medium-strength (Rp0.2 > 355 N/mm2) hybrid tubulars, where by the use of cast steel inserts the welds were removed into areas of lower stress concentration, fatigue lives higher than a factor of 100 were achieved compared to the welded nodes, even those made from StE 690. However, by the use of high-strength (Rp0.2 > 500 N/mm2) cast steel inserts and tubular members of corresponding strength, the fatigue life to crack initiation was improved by a factor of two despite a thickness reduction compared to the medium-strength design. Post-weld treatments of the welded tubulars without cast steel inserts like shot-peening, TIG-dressing, or their combination resulted only in a slight increase of fatigue life. The results of this investigation do not only show how to improve the fatigue life by a new design using cast steel inserts, but indicate also how to revise design codes from the point of damage calculation (damage sum of 0.50 for welded nodes and 0.25 for cast steel inserts instead of the conventional value of 1.00), as well as consideration of fatigue life to initiation of a technically detectable crack with a defined depth e.g., a = 1 mm.

Sign in / Sign up

Export Citation Format

Share Document