scholarly journals Grain size refinement and mechanical properties improvement in HfB2-based composites by MoSi2 addition

2021 ◽  
pp. 100197
Author(s):  
Sadjad Mashayekh ◽  
Hamid Reza Baharvandi
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Size Refinement

scholarly journals Friction Stir Processing of the Magnesium Alloy AZ61: Grain Size Refinement and Mechanical Properties

2012 ◽  
Vol 706-709 ◽  
pp. 1823-1828 ◽  
Author(s):  
J.A. del Valle ◽  
P. Rey ◽  
D. Gesto ◽  
D. Verdera ◽  
Oscar A. Ruano
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Friction Stir Processing ◽  
Superplastic Forming ◽  
Important Change ◽  
Heat Extraction ◽  
Processing Temperature ◽  
Friction Stir ◽  
Size Refinement

The effect of friction stir processing (FSP), on the microstructure and mechanical properties of a magnesium alloy AZ61 has been analyzed. This is a widely used wrought magnesium alloy provided in the form of rolled and annealed sheets with a grain size of 45 μm. The FSP was performed with an adequate cooling device in order to increase the heat extraction and reduce the processing temperature. The final microstructure showed a noticeable grain size refinement down to values close to 1.8 μm and an important change in texture. The change in texture favors basal slip during tensile testing leading to an increase of ductility and a decrease in yield stress. The stability of the grain size and the creep behavior at high temperatures were investigated. The optimum conditions for superplastic forming were determined; however, the presence of a large amount of cavities precludes the achievement of high superplastic elongations. Additionally, these results are compared with those obtained by severe hot rolling.

Optimization of Particle Size and Distribution by Hydrostatic Extrusion

2007 ◽  
Vol 561-565 ◽  
pp. 869-872 ◽  
Author(s):  
Małgorzata Lewandowska ◽  
Kinga Wawer
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Aluminium Alloys ◽  
Hydrostatic Extrusion ◽  
Nanometer Scale ◽  
Second Phase ◽  
Size Refinement ◽  
Second Phase Particles ◽  
Fatigue And Fracture

Hydrostatic extrusion (HE) as a method of metals forming is known for about 100 years. Recently, it has been utilized as an efficient way of grain size refinement down to nanometer scale. In the case of engineering metals, HE processing alters not only grain size but also second phase particles such as intermetallic inclusions and precipitates. During HE processing, these particles significantly change their size, shape and spatial distribution. These changes are accompanied by improvement in properties of processed metals such as fatigue and fracture toughness. In the present work, changes of second phase particles induced by HE are described in a quantitative way for aluminium alloys. Their impact on mechanical properties is also discussed.

scholarly journals Titanium Ti6Al4V alloy reinforced by the addition of nano yttria stabilized zirconia fabricated by selective additive manufacturing: microstructure and mechanical investigations

2020 ◽  
Vol 321 ◽  
pp. 03018
Author(s):  
Amine HATTAL ◽  
Madjid DJEMAI ◽  
Jean Jacques FOUCHET ◽  
Thierry CHAUVEAU ◽  
Brigitte BACROIX ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Mass Density ◽  
Martensite Phase ◽  
Compression Tests ◽  
Stabilized Zirconia ◽  
Powder Mixtures ◽  
Size Refinement ◽  
Heat Treated ◽  
Elongation To Failure

Additive manufactured Ti6Al4V reinforced with nano yttria-zirconia (nYSZ) parts were fabricated using selective laser melting technology (SLM). The as-received Ti6Al4V powder and two powder mixtures of Ti6Al4V mixed with several nYSZ contents (1wt% and 2.5wt%) were prepared and then SLM processed. Parts were further subjected to a stress relief heat treatment. Besides, hot isostatic pressure (HIP) was used in order to eliminate residual porosities. The pycnometer-based technique was used to measure the mass density. XRD and EBSD analysis were performed to investigate the influence of nYSZ additions on the microstructure and subsequent mechanical properties via microhardness and compression tests. It was found that addition of nYSZ increases the density of the reinforced parts and produces a fine α martensite phase. Besides, the grain size was refined compared to that of heat treated Ti6Al4V. As a consequence, a significant increase in both the hardness and the compressive strength for the reinforced Ti6Al4V were obtained while the elongation to failure was kept. These improved mechanical properties are discussed in relation to the effect of nYSZ addition, which includes latice distortions and strengthening from grain size refinement and/or α formation.

A MIM Route for Producing Ti6Al4V-TiC Composites

2016 ◽  
Vol 704 ◽  
pp. 139-147 ◽  
Author(s):  
Roger Pelletier ◽  
Louis Philippe Lefebvre ◽  
Eric Baril
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Wear Resistance ◽  
Elevated Temperatures ◽  
Metallic Matrix ◽  
High Volume ◽  
Metal Injection Molding ◽  
Titanium Matrix ◽  
Size Refinement ◽  
Specific Strength

Discontinuous reinforced titanium matrix composites have generated significant interest due to their compelling properties such as their specific strength and wear resistance at room and elevated temperatures. For these reasons, these materials have been considered in various applications such as automotive (valve components), aerospace (engine components) and medical devices (implants). Metal injection molding (MIM) has proven to be an efficient near net-shape technology suitable for high volume manufacturing of parts having complex geometries. The MIM technology is particularly attractive for producing composites as the metallic matrix does not go through the liquid state. This helps minimizing the segregation of the hard particles. MIM also reduces the needs for machining. However, the production of titanium components with the MIM process has its own challenges and limitations, such as presence of porosities and coarser microstructures compared to wrought products. The present work introduces the results obtained during the development of a MIM route for producing Ti6Al4V-5wt%TiC composites. The feedstock developed is wax-based and incorporates a pre-alloyed metal powder. The microstructure, mechanical properties at room and elevated temperatures, the wear resistance and the thermal diffusivity of the composites have been characterised. Properties are compared with those of a Ti6Al4V MIM material produced with the same feedstock and process but without TiC as well as with those of wrought Ti6Al4V reported in the literature. The presence of a small amount of TiC promotes densification and grain size refinement and affects the surface finish of the sintered components. Tensile properties of the composites are comparable or better than those of wrought Ti6Al4V (ASTM F1472). Improved mechanical properties compared to unreinforced material are associated to the higher density, finer grain size as well as solution strengthening of the titanium matrix.

scholarly journals Influence of an accumulative roll bonding (ARB) process on the properties of AA5083 Al-Mg alloy sheets

2014 ◽  
Vol 20 (4) ◽  
pp. 285-295
Author(s):  
Ana Alil ◽  
Miljana Popović ◽  
Tamara Radetić ◽  
Endre Romhanji
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Accumulative Roll Bonding ◽  
Room Temperature ◽  
Uniform Elongation ◽  
Tensile Tests ◽  
Initial Material ◽  
Type Alloy ◽  
Roll Bonding ◽  
Size Refinement

In this study, fully annealed AA5083 type alloy sheets with 1 mm in thickness were processed by accumulative roll bonding (ARB) at room temperature, up to 6 ARB cycles. It was found that microstructure was refined and mechanical properties were significantly improved with ARB processing. The maximum achieved values of hardness and tensile strength were two and three times greater than that of the initial material, respectively. This was attributed to the intensive strain hardening and grain size refinement which occurred during ARB deformation. However, the uniform elongation values were decreased by increasing the number of ARB cycles, and early fracture was registered. SEM fractography of fractured surfaces after tensile tests revealed a typical ductile fracture of ARB processed specimens, which was changed with ARB deformation. It was observed that ductile area on the fractured surfaces and the amount of necking, which occured before fracture, were decreased with increasing the number of ARB cycles. 

Improvement of Mechanical Properties of 7475 Aluminium Alloy by the Combination of SPD Processing and Annealing

2011 ◽  
Vol 690 ◽  
pp. 311-314 ◽  
Author(s):  
Kinga Wawer ◽  
Małgorzata Lewandowska ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Aluminium Alloy ◽  
True Strain ◽  
Hydrostatic Extrusion ◽  
Synergic Effect ◽  
Size Refinement ◽  
Low Temperature Annealing ◽  
Heat Treated ◽  
Precipitate Strengthening

In the present study, SPD processing was combined with annealing in order to obtain synergic effect of grain size refinement and precipitate strengthening. Samples of 7475 alloy were solution heat treated, water quenched and then subjected to hydrostatic extrusion with a total true strain of about 4. Hydrostatic extrusion resulted in a significant grain refinement from 70 mm to about 70 nm. The samples were subsequently annealed at temperatures inducing the formation of nano-precipitates. The investigations of the structure and mechanical properties of the samples subjected to SPD and annealing revealed different precipitation path in micro- and nano-grained samples. Also, it was found that the combination of HE processing and low temperature annealing results in the formation of nano-precipitates in nano-grained structures which effectively strengthen nano-aluminium alloy.

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