MICROSTRUCTURES AND MECHANICAL PROPERTIES OF ULTRAFINE GRAINED Ti-47Al-2Cr (at %) ALLOY PRODUCED USING POWDER COMPACT FORGING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1739-1744
Author(s):  
VIJAY N. NADAKUDURU ◽  
DELIANG ZHANG ◽  
PENG CAO ◽  
BRIAN GABBITTAS
Keyword(s):  
Mechanical Properties ◽  
Powder Compact ◽  
High Energy ◽  
Alloy Sample ◽  
Bulk Alloy ◽  
Porosity Level ◽  
Fine Grain ◽  
Ultrafine Grained ◽  
Powder Compacts ◽  
Innovative Techniques

Development of innovative techniques to produce gamma TiAl based alloys, with good mechanical properties, while still maintaining ultra fine grain size can be rewarding, but also is a great challenge. In the present study study a Ti -47 Al -2 Cr ( at %) alloy has been synthesized by directly forging green powder compacts of a Ti / Al / Cr composite powder produced by high energy mechanical milling of a mixture of elemental Ti , Al , Cr powders. It has been found that the density of the bulk consolidated alloy sample after forging decreases from 95% of the theoretical density in the central region to 84% in the periphery region. The microstructure of the bulk alloy consisted of several Ti rich regions, which was expected to be mainly due to initial powder condition. The room temperature tensile strength of the samples produced from this process was found to be in the range of 115 – 130 MPa. The roles of canning and green powder compact density in determining the forged sample porosity level and distribution are discussed.

Mechanical Behaviour of Ultrafine Grained Cu and Cu-(2.5 and 5) Vol.%Al2O3 Composites Produced by Powder Compact Forging

2011 ◽  
Vol 275 ◽  
pp. 170-173
Author(s):  
Aamir Mukhtar ◽  
De Liang Zhang
Keyword(s):  
Composite Powder ◽  
Powder Compact ◽  
High Energy ◽  
High Yield ◽  
High Yield Strength ◽  
High Fracture ◽  
Composite Powders ◽  
Al2o3 Composite ◽  
Ultrafine Grained ◽  
Powder Compacts

Nanostructured Cu-(2.5 and 5)vol.%Al2O3 composite powders were produced from a mixture of Cu powder and Al2O3 nanopowder using high energy mechanical milling, and then compacted by hot pressing. The Cu and Cu-Al2O3 composite powder compacts were then forged into disks at temperatures in the range of 500-800°C to consolidate the Cu and Cu-Al2O3 composite powders. Tensile testing of the specimens cut from the forged disks showed that the Cu forged disk had a good ductility (plastic strain to fracture: ~15%) and high yield strength of 320 MPa, and the Cu-(2.5 and 5)vol.%Al2O3 composite forged disks had a high fracture strength in range of 530-600 MPa, but low ductility.

Consolidation of Titanium, and Ti-6Al-4V Alloy Powders by Powder Compact Forging

2009 ◽  
Vol 618-619 ◽  
pp. 513-516 ◽  
Author(s):  
De Liang Zhang ◽  
Stella Raynova ◽  
Vijay Nadakuduru ◽  
Peng Cao ◽  
Brian Gabbitas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Powder Compact ◽  
Materials Science ◽  
Value Added ◽  
Cost Effective ◽  
Porosity Level ◽  
Open Die Forging ◽  
Powder Compacts ◽  
Limited Depth

Consolidation of titanium and titanium alloy powders using thermomechanical powder metallurgy (TPM) processes (powder compact forging, extrusion and rolling) is one way that can lead to cost-effective production of high value-added consolidated titanium and titanium alloy products such as near-net shaped components, tubes and plates. This paper provides an overview of the quality, microstructure (to limited depth), porosity level and mechanical properties of disks produced using open die forging of powder compacts of CP titanium and Ti-6Al-4V alloy powders. The general materials science principles underlying the relationships between processing conditions, microstructure and the mechanical properties of the disks made by using the powder compact forging are discussed.

Microstructure and Mechanical Behaviour of Ultrafine Grained Al-4wt%Cu-(2.5-10) Vol.% SiC Metal Matrix Composites Produced by Powder Compact Forging

2011 ◽  
Vol 275 ◽  
pp. 208-213
Author(s):  
A. Gazawi ◽  
De Liang Zhang ◽  
K.L. Pickering ◽  
Aamir Mukhtar
Keyword(s):  
Metal Matrix ◽  
Powder Compact ◽  
Volume Fraction ◽  
High Energy ◽  
Matrix Composites ◽  
Plastic Yielding ◽  
Composite Powders ◽  
Ultrafine Grained ◽  
Powder Compacts ◽  
Small Plastic Strain

Ultrafine grained Al-4wt%Cu-(2.5-10) vol.% SiC metal matrix composite powders were produced from a mixture of Al, Cu and SiC powders using high energy mechanical milling (HEMM). The composite powders produced were first hot pressed at 300°C with a pressure of 240 MPa to produce cylindrical powder compacts with a relative density in the range of 80-94% which decreased with increasing the SiC volume fraction. Powder compact forging was utilized to consolidate the powder compacts into nearly fully dense forged disks. With increasing the volume fraction of SiC from 2.5% to 10%, the average microhardness of the forged disks increased from 73HV to 162HV. The fracture strength of the forged disks increased from 225 to 412 MPa with increasing the volume fraction of SiC particles from 2.5 to 10%. The Al-4wt%Cu-2.5vol.%SiC forged disk did not show any macroscopic plastic yielding, while the Al-4wt%Cu-(7.5 and 10)vol.% SiC forged disk showed macroscopic plastic yielding with a small plastic strain to fracture (~1%).

The Influence of High-Energy Ball Milling and Sintering Process on the Microstructure and Mechanical Properties of Al-Ni-Y-Co-La Alloy

2013 ◽  
Vol 745-746 ◽  
pp. 281-285
Author(s):  
Y.B. Yuan ◽  
Rui Xiao Zheng ◽  
Su Jing Ge ◽  
Han Yang ◽  
Chao Li Ma
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Ball Milling ◽  
Amorphous Materials ◽  
Volume Fraction ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Process Conditions ◽  
Bulk Alloy ◽  
Energy Ball

Al86Ni7Y4.5Co1La1.5 (at.%) alloy powder was produced by argon gas atomization process. After high-energy ball milling, the powder was consolidated and extruded by using vacuum hot press sintering under different process conditions, sintering temperature, extrusion pressure, sintering time, etc.. The microstructure and morphology of the powder and consolidated bulk alloy were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The phase transformation of the powder was investigated by differential scanning calorimetry (DSC). Mechanical properties of the consolidated bulk alloy were examined. The results showed that as the milling time increase, the volume fraction of amorphous materials and the hardness and yield strength of the bulk alloy were obvious improved.

scholarly journals SEPARATION OF THE INTER- AND INTRA-PARTICLE POROSITY IN IMAGES OF POWDER COMPACTS

2011 ◽  
Vol 21 (3) ◽  
pp. 183
Author(s):  
Jacques Lacaze ◽  
Alexis Arnal ◽  
Jean-Luc Dupuy ◽  
Dominique Poquillon
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Satisfactory Agreement ◽  
Compaction Pressure ◽  
High Porosity ◽  
Porosity Level ◽  
Iron Powders ◽  
Cheap Method ◽  
Two Parameters ◽  
Powder Compacts

Powder metallurgy is a highly developed and cheap method of manufacturing reliable materials, either metallic, ceramic or composite. This process was used to make green compacts of iron powders with a high porosity level. This study is part of a project aimed at describing the relationships between mechanical properties and morphological features of such compacts, with particular attention paid to the shape of the grains and the compaction pressure. In this report, a method is proposed to separate the intra grain porosity from the cavities located between particles. The approach is based on the covariogram of images obtained from the surface of the compacts by means of a laser roughometer. To achieve this separation, a model of the structure is proposed which assumes that the distributions of the grains and of the intra-particle cavities are random and independent. Each distribution is characterized by two parameters. A satisfactory agreement is obtained between experimental and calculated covariograms after identification of these parameters.

Comparison of Blended Elemental (BE) and Mechanical Alloyed (MA) Powder Compact Forging into Ti-6Al-4V Rocker Arms

2012 ◽  
Vol 520 ◽  
pp. 82-88 ◽  
Author(s):  
Ming Tu Jia ◽  
De Liang Zhang ◽  
Brian Gabbitas
Keyword(s):  
Master Alloy ◽  
Internal Combustion Engines ◽  
Powder Compact ◽  
High Energy ◽  
Combustion Engines ◽  
Alloyed Powder ◽  
Blended Elemental ◽  
Blended Powder ◽  
Forged Parts ◽  
Powder Compacts

Ti-6Al-4V rocker arms for internal combustion engines were produced by forging of compacts of blended powder consisting of elemental hydride-dehydride (HDH) titanium powder and Al60V40 (wt%) master alloy powder or mechanical alloyed (MA) powder synthesized by high energy mechanical milling of a mixture of HDH titanium and Al60V40 master alloy powders. The powder compacts were made by warm compaction, and their relative density was 90%. The mechanical properties and microstructures of as-forged parts made using blended powder were improved significantly with increasing holding time at forging temperature, and close to those of as-forged parts produced by powder compact forging of HDH Ti-6Al-4V pre-alloyed powder. However, the as-forged part produced by powder compact forging of MA powder was brittle, and fractured prematurely during tensile testing.

Powder Consolidation of Titanium and Titanium Alloys by a Powder Compact Forging Process

2016 ◽  
Vol 704 ◽  
pp. 68-74 ◽  
Author(s):  
Ming Tu Jia ◽  
Brian Gabbitas
Keyword(s):  
Mechanical Properties ◽  
Powder Compact ◽  
Titanium Powder ◽  
Full Density ◽  
Low Oxygen ◽  
Powder Consolidation ◽  
Forging Process ◽  
Cp Ti ◽  
Field Assisted Sintering ◽  
Powder Compacts

Powder compact forging in combination with induction sintering, a field assisted sintering technique (FAST), was used to produce commercially pure (CP) Ti and Ti-13V-11Cr-3Al parts. Green powder compacts with high relative density were manufactured by cold compaction and warm compaction, respectively. During the powder compact forging process, CP titanium powder was consolidated completely to produce a near net shaped top cover for a diving helmet with full density and good mechanical properties. Also, a Ti-13V-11Cr-3Al alloy was fully consolidated into a cylinder using blended elemental powders. As a comparison, raw titanium powder with different oxygen contents was used to make a Ti-13V-11Cr-3Al powder compact forging. Using a starting powder with low oxygen content, a forged cylinder with good mechanical properties was produced.

Ultrafine and Nanostructured Refractory Metals Processed by SPD: Microstructure and Mechanical Properties

2008 ◽  
Vol 579 ◽  
pp. 75-90 ◽  
Author(s):  
Q. Wei ◽  
K.T. Ramesh ◽  
Laszlo J. Kecskes ◽  
Suveen N. Mathaudhu ◽  
K.T. Hartwig
Keyword(s):  
Mechanical Properties ◽  
High Energy ◽  
Refractory Metals ◽  
Face Centered Cubic ◽  
Future Directions ◽  
Fcc Metals ◽  
The Past ◽  
Microstructure And Mechanical Properties ◽  
Ultrafine Grained ◽  
Face Centered

Severe plastic deformation (SPD) has been demonstrated to be the most efficient method to produce bulk metals with ultrafine grained (UFG, 100 nm < grain size d < 500 nm) and nanocrystalline (NC, d<100 nm) microstructures. Such metals exhibit some unique properties owing to their unusual microstructures such as high-energy, non-equilibrium grain boundaries. Efforts in the past two decades have focused on metals with face-centered cubic (fcc) structures. Recent experimental results have shown that UFG/NC metals with body-centered cubic (bcc) structures have some properties that are distinct from their fcc counterparts. Further, the majority of the fcc metals are very ductile and have relatively low melting points, making them easier to process using SPD. On the contrary, many bcc metals are refractory, and are very sensitive to interstitial impurities, rendering them difficult to work via SPD. In this article, we attempt to summarize the state-of-the-art of UFG/NC refractory metals processed by SPD, with focus on the microstructure and mechanical properties. Comparisons with UFG/NC fcc metals are made where appropriate. Outstanding issues and future directions are also addressed.

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