scholarly journals Properties Comparison of Ti-Al-Si Alloys Produced by Various Metallurgy Methods

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3084 ◽  
Author(s):  
Anna Knaislová ◽  
Pavel Novák ◽  
Jaromír Kopeček ◽  
Filip Průša
Keyword(s):  
Fracture Toughness ◽  
Phase Composition ◽  
Powder Metallurgy ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Compression Tests ◽  
Large Area ◽  
Fine Grained ◽  
Central Porosity ◽  
Fine Grained Structure

Melting metallurgy is still the most frequently used and simplest method for the processing of metallic materials. Some of the materials (especially intermetallics) are very difficult to prepare by this method due to the high melting points, poor fluidity, or formation of cracks and pores after casting. This article describes the processing of Ti-Al-Si alloys by arc melting, and shows the microstructure, phase composition, hardness, fracture toughness, and compression tests of these alloys. These results are compared with the same alloys prepared by powder metallurgy by the means of a combination of mechanical alloying and spark plasma sintering. Ti-Al-Si alloys processed by melting metallurgy are characterized by a very coarse structure with central porosity. The phase composition is formed by titanium aluminides and titanium silicides, which are full of cracks. Ti-Al-Si alloys processed by the powder metallurgy route have a relatively homogeneous fine-grained structure with higher hardness. However, these alloys are very brittle. On the other hand, the fracture toughness of arc-melted samples is immeasurable using Palmqvist’s method because the crack is stopped by a large area of titanium aluminide matrix.

scholarly journals Effect of Microstructure and Notches on the Fracture Toughness of Medium Carbon Steel

1970 ◽  
Vol 3 (1) ◽  
pp. 15-22 ◽  
Author(s):  
SK Nath ◽  
Uttam Kr Das
Keyword(s):  
Fracture Toughness ◽  
Carbon Steel ◽  
Tensile Specimen ◽  
Medium Carbon Steel ◽  
Notch Angle ◽  
Medium Carbon ◽  
Fine Grained ◽  
Keywords Fracture ◽  
Fine Grained Structure ◽  
Marine Engineering

Fracture toughness (K1C) of medium carbon steel (0.5% C) has been determined by round notched tensile specimen. Two notch diameters (5.6mm and 4.2mm) and three notch angles (α) namely 45°, 60° and 75° have been used to observe the effect of notch diameters and notch angle on fracture toughness of the steel. By heat treatment the microstructure of the steel is also varied and its effect on the fracture toughness is also observed. It has been found that fine grained structure improves fracture toughness. Lower notch diameter and higher notch angle show higher value of K1C. Keywords: Fracture toughness, microstructure, notch, heat treatmentDOI: 10.3329/jname.v3i1.925 Journal of Naval Architecture and Marine Engineering 3(2006) 15-22

Precipitation Phenomena and Strain Hardening of Intermetallic Titanium Aluminides

2002 ◽  
Vol 753 ◽  
Author(s):  
J. Müllauer ◽  
F. Appel
Keyword(s):  
Work Hardening ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Titanium Boride ◽  
Compression Tests ◽  
Two Phase ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Work Hardening Coefficient ◽  
Precipitation Phenomena

ABSTRACTIn two-phase titanium aluminide alloys, the implementation of precipitation reactions is a widely utilized concept to control the microstructure and strengthen the material. A study has been made on the influence of carbide and boride precipitates on dislocation mobility and strengthening at 300 K. Compression tests were carried out for characterizing the mechanisms determining flow stress and dislocation glide resistance. The interaction mechanisms between the precipitates and dislocations were assessed by thermodynamic glide parameters and transmission electron microscopy. It has been shown that small titanium boride precipitates and carbide precipitates of perovskite type act as long-range dislocation glide obstacles. The interaction between the dislocations and the borides and carbides mainly leads to an athermal stress contribution. However, the dislocation-particle interactions are quite different. Small groups of borides are encircled by dislocations. This gives rise to the formation of loop structures the density of which increases with strain. On the contrary, the carbide precipitates are shearable and can be overcome without Orowan looping. This different behaviour is also reflected in the work hardening characteristics. Whereas the work hardening coefficient of the boron doped material increases with increasing B-concentration, it is independent of concentration in the case of the carbon-doped material.

Bonding γ-TiAl Alloys Using Ti/Al Nanolayers Doped with Ag

2008 ◽  
Vol 587-588 ◽  
pp. 488-491 ◽  
Author(s):  
Liliana I. Duarte ◽  
Filomena Viana ◽  
Manuel F. Vieira ◽  
Ana Sofia Ramos ◽  
M. Teresa Vieira ◽  
...  
Keyword(s):  
Solid State ◽  
Diffusion Bonding ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Bonding Temperature ◽  
Bonding Interface ◽  
Chemical Compositions ◽  
Solid State Diffusion ◽  
Fine Grained ◽  
State Diffusion

Successful solid state bonding of titanium aluminides requires the use of high temperature and pressure. In previous works, authors have demonstrated that the use of Ti/Al multilayer thin film as an interlayer, deposited by d.c. magnetron sputtering onto the joining surfaces, can effectively lower the bonding temperature. The enhanced diffusivity of these nanometric layers and the heat evolved by the formation of γ-TiAl improves the joinability of titanium aluminide by solid-state diffusion bonding. In the present work, further improvement of the process was pursued by doping the interlayer with 2.8 at.% of Ag; previous studies have confirmed that silver favours the transformation Ti+Al→γ-TiAl. The solid-state diffusion bonding experiments were performed in vacuum by applying 50 MPa at 900°C for 1 h. The effect of the third element on the microstructure and chemical composition along the bonding interface has been analyzed. Microstructural characterisation of the interface was performed by scanning and transmission electron microscopy. Chemical compositions were analysed by energy dispersive X-ray spectroscopy. No defects were observed at the interface and sound bonding was achieved between the interlayers and base γ-TiAl. The bonding interface shows a fine-grained microstructure, slightly coarser than the one formed at the same temperature with the undoped Ti/Al multilayer.

The Formation of Fine-Grained Structure in S304H-Type Austenitic Stainless Steel during Hot-To-Warm Working

2012 ◽  
Vol 715-716 ◽  
pp. 380-385 ◽  
Author(s):  
Marina Tikhonova ◽  
Valeriy Dudko ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Compression Tests ◽  
Scale Level ◽  
Single Pass ◽  
Fine Grained ◽  
Loading Direction ◽  
Fine Grained Structure ◽  
Multiple Compression ◽  
The Relationship

The dynamic process of grain evolution in a Super304H austenitic stainless steel was studied in compression tests. The tests were carried out to a strain of 0.7 at temperatures ranging from 700 to 1000°C and strain rate of 10-3s-1. In addition to single pass compression the multiple compressions with changing the loading direction in 90o and decreasing the temperature with step of 100°C from 1000 to 700°C in each pass were utilized to achieve large cumulative strains. Under multiple compression the values of flow stresses were lower than those at single-pass compressions under the same temperatures. The fraction of dynamically recrystallized grains decreased from 1.0 to almost zero with decreasing temperature in single-pass compressions. On the other hand, almost fully recrystallized structure developed under conditions of multiple compressions. The size of dynamically recrystallized grains decreased with decreasing the deformation temperature, approaching a submicrometer scale level at 700°C. The relationship between the deformation conditions and operating mechanisms of dynamic recrystallization is discussed in some details.

scholarly journals Possibilities of Manufacturing Products from Cermet Compositions Using Nanoscale Powders by Additive Manufacturing Methods

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3425 ◽  
Author(s):  
Sergei Grigoriev ◽  
Tatiana Tarasova ◽  
Andrey Gusarov ◽  
Roman Khmyrov ◽  
Sergei Egorov
Keyword(s):  
Fracture Toughness ◽  
Wear Resistance ◽  
Phase Composition ◽  
Powder Metallurgy ◽  
Traditional Method ◽  
Laser Melting ◽  
Precision Engineering ◽  
Manufacturing Methods ◽  
Engineering Industries ◽  
Powder Metallurgy Methods

Complicated wear-resistant parts made by selective laser melting (SLM) of powder material based on compositions of metal and ceramics can be widely used in mining, oil engineering, and other precision engineering industries. Ceramic–metal compositions were made using nanoscale powders by powder metallurgy methods. Optimal regimes were found for the SLM method. Chemical and phase composition, fracture toughness, and wear resistance of the obtained materials were determined. The wear rate of samples from 94 wt% tungsten carbide (WC) and 6 wt% cobalt (Co) was 1.3 times lower than that of a sample from BK6 obtained by the conventional methods. The hardness of obtained samples 2500 HV was 1.6 times higher than that of a sample from BK6 obtained by the traditional method (1550 HV).

scholarly journals Regularities of the formation and features of the influence of a fine structure on the properties of a new-generation magnesium alloy

2020 ◽  
pp. 55-63
Author(s):  
E. F. Volkova ◽  
V. A. Duyunova ◽  
I. V. Mostyaev ◽  
M. V. Akinina
Keyword(s):  
Fine Structure ◽  
Phase Composition ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
High Strength ◽  
Fine Grained ◽  
Long Period ◽  
Noticeable Improvement ◽  
Fine Grained Structure ◽  
New Generation

An approach to creating high-strength deformable magnesium alloys for developing a fine-grained structure and a favourable phase composition is considered. The possibility of a noticeable improvement in the characteristics of magnesium alloys by introducing REEs in certain ratios for the formation of long-period phases (LPSO phases) is considered. The regularities of formation and features of the influence of a fine structure on the properties of a new-generation magnesium alloy of the VMD16 brand are studied.

Phase composition, microstructure and properties of aluminosilicate lightweight materials obtained by the method of burnable additives

2020 ◽  
pp. 3-9
Author(s):  
M. Kh. Rumi ◽  
Sh. K. Irmatova ◽  
Sh. A. Fayziev ◽  
M. A. Zufarov ◽  
E. P. Mansurova ◽  
...  
Keyword(s):  
Phase Composition ◽  
Phase Formation ◽  
Fractional Composition ◽  
Raw Materials ◽  
Lightweight Materials ◽  
Microstructure And Properties ◽  
Fine Grained ◽  
Black Clay ◽  
Fine Grained Structure ◽  
Alkaline Oxides

The nature of phase formation and the properties of aluminosilicate lightweight materials created from raw materials from the Angren and Samarkand deposits of Uzbekistan are studied. The phase composition, microstructure, and physicotechnical properties of the compositions with the addition of plastic black clay and a burnable additive in the form of coke of various fractional composition were determined. It is shown that the materials of the Angrenskoye deposit are more prone to cristobalitization, which is due to the low content of alkaline oxides and a fine-grained structure. The optimum complex of properties is possessed by lightweights based on cracked clay with a burnable additive in the form of polyfraction coke. Ill. 3. Ref. 13. Tab. 2.

DILLIMAX 690

Alloy Digest ◽  
2012 ◽  
Vol 61 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Physical Properties ◽  
Structural Steel ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
Fine Grained ◽  
Minimum Yield

Abstract Dillimax 550 is a high-strength quenched and tempered, fine-grained structural steel with a minimum yield strength of 690 MPa (100 ksi). Plate is delivered in three qualities: basic, tough, and extra tough. This datasheet provides information on composition, physical properties, and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, and joining. Filing Code: SA-652. Producer or source: Dillinger Hütte GTS.

DILLIMAX 500

Alloy Digest ◽  
2012 ◽  
Vol 61 (3) ◽  
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Physical Properties ◽  
Structural Steel ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
Fine Grained ◽  
High Toughness ◽  
Minimum Yield

Abstract Dillimax 500 is a high-strength quenched and tempered, fine-grained structural steel with a minimum yield strength of 500 MPa (72 ksi). Plate is delivered in three qualities: basic, high toughness, and extra tough. This datasheet provides information on composition, physical properties, and tensile properties as well as fracture toughness. It also includes information on surface qualities as well as forming, heat treating, and joining. Filing Code: SA-645. Producer or source: Dillinger Hütte GTS.

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