Production of Aerospace Tial Intermetallics for High Temperature Applications by Powder Metallurgy

2012 ◽  
Vol 727-728 ◽  
pp. 44-49
Author(s):  
V.A.R. Henriques ◽  
A.C.S.M. Dutra ◽  
C.A.A. Cairo
Keyword(s):  
Powder Metallurgy ◽  
Complex Geometry ◽  
Lamellar Microstructure ◽  
Turbine Engines ◽  
Tial Alloys ◽  
Metallographic Preparation ◽  
Near Net Shape ◽  
Low Costs ◽  
Work Samples ◽  
Compound Tial

During the recent years, alloys based on the intermetallic compound TiAl have attracted a considerable interest as potential competitors to steels and superalloys. Gamma-TiAl alloys are potential replacements for nickel and conventional titanium alloys in hot sections of turbine engines, as well as in orbital platform vehicles. The alloy design and efficient routes of TiAl processing are important technological challenges. Powder metallurgy is a near net shape process that allows the parts production with complex geometry at low costs. In this work, samples of Ti-48Al-2Cr-2Nb (at.%) were prepared from elemental and pre-alloyed powders mixed for 2 h, followed by cold uniaxial and isostatic pressing and sintered between 800 up to 1400°C, for 1 h, under vacuum. After metallographic preparation, sintered samples were characterized by SEM (Scanning Electron Microscopy), density analyses and Vickers microhardness measurements. The results indicated the viability of the pre-alloyed route and the tendency of a full lamellar microstructure of alternating gamma and α2 phases in high sintering temperatures.

Microstructural Investigation of Routes for Gamma Titanium Aluminides Production by Powder Metallurgy

2016 ◽  
Vol 704 ◽  
pp. 204-213 ◽  
Author(s):  
V.A.R. Henriques ◽  
E.T. Galvani ◽  
Carlos Alberto Alves Cairo ◽  
M.L.A. Graça ◽  
A.C.S.M. Dutra
Keyword(s):  
Powder Metallurgy ◽  
Hot Pressing ◽  
Titanium Aluminides ◽  
Lamellar Microstructure ◽  
Grain Structure ◽  
Turbine Engines ◽  
X Ray Diffraction ◽  
Microstructural Investigation ◽  
Tial Alloys ◽  
Aerospace Systems

The alloy design and efficient routes of TiAl processing are important technological challenges for the development of new aerospace systems. Gamma-TiAl alloys are potential replacements for nickel and conventional titanium alloys in hot sections of turbine engines, as well as in sub-structures of orbital platform vehicles. Powder metallurgy (P/M) of Ti-based alloys may lead to the obtainment of components having weak-to-absent textures, uniform grain structure and higher homogeneity compared with conventional wrought products. This paper aims to investigate the microstructural evolution and densification aspects involved in the obtainment of Ti-48Al-2Cr-2Nb (at.%) alloy by three P/M-processing routes. Samples were prepared from elemental and pre-alloyed powders mixed for 2 h, followed by cold uniaxial and isostatic pressing followed by sintering and hot pressing stages between 1100°C up to 1400°C, for 1 h. After metallographic preparation, sintered samples were characterized by means of scanning electron microscopy (SEM) in the backscattered mode (BSE), X-ray diffraction (XRD), and density measurements. The results showed the potential of TiAl pre-alloyed powders to prevent Kirkendall porosity. A full lamellar microstructure was obtained by the pressureless route while a duplex microstructure was observed in samples produced by the hot pressing route.

Effect of Container on the Microstructure and Properties of Powder Metallurgy TiAl Alloys

2015 ◽  
Vol 817 ◽  
pp. 604-609
Author(s):  
Jie Wu ◽  
Lei Xu ◽  
Zheng Guan Lu ◽  
Rui Peng Guo ◽  
Yu You Cui ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Mild Steel ◽  
Tial Alloy ◽  
Complex Shape ◽  
Pure Titanium ◽  
Tial Alloys ◽  
Microstructure And Properties ◽  
Commercial Pure Titanium ◽  
Near Net Shape ◽  
Cp Ti

Pre-alloyed powder of Ti-47Al-2Cr-2Nb-0.15B was prepared by a gas atomization process and powder metallurgy (PM) γ-TiAl alloys were made through a hot isostatic pressed (HIPed) route. The atomized powders were canned in containers, degassed, sealed, and HIPed. Effect of two different canning materials (mild steel and commercial pure titanium (CP-Ti)) on the microstructure and properties of as-HIPed γ-TiAl alloy were discussed. Due to the reaction between mild steel containers and γ-TiAl at relative high temperature (over 1230 °C), the γ-TiAl matrix is contaminated. CP-Ti canned γ-TiAl showed bigger yield and fracture strength than mild steel canned TiAl. PM γ-TiAl alloy parts having complex shape could be manufactured by the near net-shape process.

Microstructures and Creep Properties of Powder Metallurgy Ti-48Al-2Cr-2Nb + W

2007 ◽  
Author(s):  
H. Saari ◽  
S. Bulmer ◽  
D. Y. Seo ◽  
P. Au
Keyword(s):  
Heat Treatment ◽  
Powder Metallurgy ◽  
Lamellar Microstructure ◽  
Controlled Cooling ◽  
Tial Alloys ◽  
Creep Properties ◽  
Rupture Ductility ◽  
Heat Treated ◽  
Fully Lamellar ◽  
Lamellar Interfaces

The microstructures and creep properties at 760 °C and 276 MPa of three powder metallurgy TiAl alloys (Ti-48Al-2Cr-2Nb, Ti-48Al-2Cr-2Nb+0.5W, and Ti-48Al-2Cr-2Nb+1W (atomic percent)) are presented. The results indicate that the addition of W to the base composition, the use of a solution heat treatment combined with controlled cooling (to generate a fully lamellar microstructure), and the use of an aging heat treatment (to generate precipitate particles at the lamellar interfaces) improve creep properties dramatically. The solution heat treated and aged Ti-48Al-2Cr-2Nb+1W alloy has a time to 0.5% strain of 8.3 hours, a time to 1% strain of 46.4 hours, and a creep life of 412 hours with a rupture ductility of 16.9%.

Sintering of a Gamma Ti-Al Alloy

2006 ◽  
Vol 530-531 ◽  
pp. 10-15 ◽  
Author(s):  
Vinicius André Rodrigues Henriques ◽  
Carlos Alberto Alves Cairo ◽  
D.S. Almeida ◽  
Mario Lima de Alencastro Graça
Keyword(s):  
Phase Structure ◽  
Complex Geometry ◽  
Cold Isostatic Pressing ◽  
Turbine Engines ◽  
Al Alloy ◽  
Two Phase ◽  
Good Oxidation Resistance ◽  
Microstructure Modification ◽  
Near Net Shape ◽  
Α2 Phase

Gamma-TiAl alloys are potential replacements for nickel alloys and conventional titanium alloys in the cooler sections of turbine engines, as well as in orbital platform vehicles. The combination of high specific stiffness and good oxidation resistance at intermediate temperatures can provide significant weight savings. However, they have a limited plasticity at room temperature and the tendency to brittle fracture. Powder metallurgy is a near net shape process that allows the parts production with complex geometry at low costs. An improved plasticity of the Ti-Al alloys is received by adding alloying elements and by microstructure modification. An alloy of two-phase structure Ti–48Al–2Cr–2Nb (at.%) was investigated using the blended elemental technique. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering at 1500 °C, in vacuum. It was shown that the samples presented a two-phase structure consisting of lamellar colonies of alternating layers of gamma and α2 phase.

Preparation of Titanium Alloy Parts by Powder Compact Extrusion of a Powder Mixture and Scaled up Manufacture

2016 ◽  
Vol 704 ◽  
pp. 75-84 ◽  
Author(s):  
Fei Yang ◽  
Brian Gabbitas ◽  
Ajit Pal Singh ◽  
Stella Raynova ◽  
Hui Yang Lu ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Powder Metallurgy ◽  
Titanium Alloys ◽  
Powder Mixture ◽  
Powder Compact ◽  
Blended Elemental ◽  
Pilot Plant Scale ◽  
Near Net Shape ◽  
Titanium Processing ◽  
The University

Blended Elemental Powder Metallurgy (BE-PM) is a very attractive method for producing titanium alloys, which can be near-net shape formed with compositional freedom. However, a minimization of oxygen pick-up during processing into manufactured parts is a big challenge for powder metallurgy of titanium alloys. In this paper, different approaches for preparing titanium alloy parts by powder compact extrusion with 0.05-0.1wt.% of oxygen pick-up during manufacturing are discussed. The starting materials were a powder mixture of HDH titanium powder, other elemental powders and a master alloy powder. Different titanium alloys and composites, such as Ti-6Al-4V, Ti-4Al-4Sn-4Mo-0.5Si, Ti-5Al-5V-5Mo-3Cr, and Ti-5Al-5V-5Mo-3Cr-5vol%TiB, with different profiles such as round and rectangular bars, a wedge profile, wire and tubes have been successfully manufactured on a laboratory and pilot-plant scale. Furthermore, a possible route for scaling up the titanium processing capabilities in the University of Waikato has also been discussed.

scholarly journals Chemical heterogeneities in tungsten containing TiAl alloys processed by powder metallurgy

Materialia ◽  
2021 ◽  
pp. 101147
Author(s):  
Alain Couret ◽  
Melissa Allen ◽  
Marcus Willi Rackel ◽  
Benjamin Galy ◽  
Jean-Philippe Monchoux ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Tial Alloys

Powder Metallurgy Aluminum Alloys: Structure and Porosity

2019 ◽  
Author(s):  
Will Judge ◽  
Georges Kipouros
Keyword(s):  
Powder Metallurgy ◽  
Aluminum Alloys ◽  
Material Properties ◽  
Cost Effective ◽  
High Reactivity ◽  
Commercial Production ◽  
Processing Conditions ◽  
Near Net Shape ◽  
And Performance ◽  
Production Conditions

The production of aluminum alloys through powder metallurgy (PM) processes allows for the manufacture of net- or near-net-shape components in a cost-effective and sustainable manner. The high reactivity of aluminum metal, however, complicates PM processing, and special attention must be given to certain steps during production, particularly sintering. PM processing conditions strongly affect the structure and porosity of aluminum PM alloys, which ultimately determine their material properties and performance. In this article, the fundamental aspects of the commercial production of aluminum PM alloys are presented, along with the effects of production conditions on the structure and porosity of aluminum PM alloys. The properties and performance of aluminum PM alloys are then analyzed and interpreted with respect to their structure and porosity.

Effect of Alloying and Thermal Processing on Mechanical Properties of TiAl Alloys

2016 ◽  
Vol 258 ◽  
pp. 501-505
Author(s):  
Alice Chlupová ◽  
Milan Heczko ◽  
Karel Obrtlík ◽  
Přemysl Beran ◽  
Tomáš Kruml
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Processing ◽  
Lamellar Microstructure ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Tial Alloys ◽  
Working Temperature ◽  
Β Phase ◽  
Strength And Ductility

Two γ-based TiAl alloys with 7 at.% of Nb, alloyed with 2 at.% Mo and 0.5 at.% C, were studied. A heat treatment leading to very fine lamellar microstructure was applied on both alloys. Microstructure after the heat treatment was described and mechanical properties including fatigue behaviour were measured. The as-received material alloyed with C possesses high strength and very limited ductility, especially at RT. After application of selected heat treatment it becomes even more brittle; therefore, this process could be considered as not appropriate for this alloy. On the contrary, in the case of Mo alloyed material, both strength and ductility are improved by the heat treatment at RT and usual working temperature (~750 °C). Presence of the β phase is responsible for this effect. The selected heat treatment thus can be an alternative for this alloy to other thermomechanical treatments as high temperature forging.

scholarly journals Microstructure and Mechanical Properties of Sintered and Heat-Treated HfNbTaTiZr High Entropy Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1324 ◽  
Author(s):  
Jaroslav Málek ◽  
Jiří Zýka ◽  
František Lukáč ◽  
Jakub Čížek ◽  
Lenka Kunčická ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Dendritic Structure ◽  
Cold Isostatic Pressing ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Arc Melting ◽  
Powder Metallurgy Process ◽  
Heat Treated ◽  
Near Net Shape ◽  
Metallurgy Process

High entropy alloys (HEAs) have attracted researchers’ interest in recent years. The aim of this work was to prepare the HfNbTaTiZr high entropy alloy via the powder metallurgy process and characterize its properties. The powder metallurgy process is a prospective solution for the synthesis of various alloys and has several advantages over arc melting (e.g., no dendritic structure, near net-shape, etc.). Cold isostatic pressing of blended elemental powders and subsequent sintering at 1400 °C for various time periods up to 64 h was used. Certain residual porosity, as well as bcc2 (Nb- and Ta-rich) and hcp (Zr- and Hf-rich) phases, remained in the bcc microstructure after sintering. The bcc2 phase was completely eliminated during annealing (1200 °C/1h) and subsequent water quenching. The hardness values of the sintered specimens ranged from 300 to 400 HV10. The grain coarsening during sintering was significantly limited and the maximum average grain diameter after 64 h of sintering was approximately 60 μm. The compression strength at 800 °C was 370 MPa and decreased to 47 MPa at 1200 °C. Porosity can be removed during the hot deformation process, leading to an increase in hardness to ~450 HV10.

scholarly journals Processing of Elemental Titanium by Powder Metallurgy Techniques

2013 ◽  
Vol 765 ◽  
pp. 383-387 ◽  
Author(s):  
Leandro Bolzoni ◽  
E.M. Ruiz-Navas ◽  
Elena Gordo
Keyword(s):  
Powder Metallurgy ◽  
Automotive Industry ◽  
Aerospace Industry ◽  
High Strength ◽  
Production Costs ◽  
Fine Grained ◽  
Good Corrosion Resistance ◽  
Fabrication Cost ◽  
Near Net Shape ◽  
Industrial Level

Titanium is characterised by an outstanding combination of properties like high strength, low density, good corrosion resistance and biocompatibility. Nonetheless, widespread employment of titanium at the industrial level, especially in the automotive industry, has not been achieved yet because of its high extraction and production costs. Consequently, titanium finds applications mainly in high demanding sectors, such as the aerospace industry or to produce biomedical devices, where the final high cost is not the principal issue. The processing of titanium and its alloys by means of powder metallurgy (PM) techniques is claimed to be a suitable way to reduce the fabrication cost of titanium products as well as offering the possibility to design new alloys which are difficult to obtain using the conventional metallurgical route, for example due to segregation of heavy alloying elements. This work deals with the processing of hydride-dehydride elemental titanium powder by means of different PM methods and aims at investigating the processing of near net-shape, chemically-homogeneous and fine-grained titanium-based components. In particular, properties achievable (i.e. relative density, microstructure and mechanical properties) and problems related to the processing of elemental titanium, by both the conventional PM route of pressing and sintering and the advanced PM method of hot-pressing, are presented.

Sign in / Sign up

Export Citation Format

Share Document