Fabrication of carbide-particle-reinforced titanium aluminide-matrix composites by laser-engineered net shaping

2004 ◽  
Vol 35 (3) ◽  
pp. 1133-1140 ◽  
Author(s):  
Weiping Liu ◽  
J. N. DuPont
2019 ◽  
Vol 25 (3) ◽  
pp. 581-591 ◽  
Author(s):  
Fuda Ning ◽  
Yingbin Hu ◽  
Weilong Cong

Purpose The purpose of this paper is to identify if the implementation of ultrasonic vibration in laser engineered net shaping (LENS) process can help to reduce internal weaknesses such as porosity, coarse primary TiB whisker and heterogeneous distribution of TiB reinforcement in the LENS-fabricated TiB reinforced Ti matrix composites (TiB-TMC) parts. Design/methodology/approach An experimental investigation is performed to achieve the results for comparative studies under different fabrication conditions through quantitative data analysis. An approach of microstructural characterization and mechanical testing is conducted to obtain the output attributes. In addition, the theoretical analysis of the physics of ultrasonic vibration in the melting materials is presented to explain the influences of ultrasonic vibration on the microstructural evolution occurred in the part fabrication. Findings Because of the nonlinear effects of acoustic streaming and cavitation induced by ultrasonic vibration, porosity is significantly reduced and a relatively small variation of pore sizes is achieved. Ultrasonic vibration also causes the formation of smaller TiB whiskers that distribute along grain boundaries with a homogeneous dispersion. Additionally, a quasi-continuous network (QCN) microstructure is considerably finer than that produced by LENS process without ultrasonic vibration. The refinements of both reinforcing TiB whiskers and QCN microstructural grains further improve the microhardness of TiB-TMC parts. Originality/value The novel ultrasonic vibration-assisted (UV-A) LENS process of TiB-TMC is conducted in this work for the first time to improve the process performance and part quality.


Author(s):  
J. Y. Hwang ◽  
A. R. P. Singh ◽  
R. Banerjee ◽  
J. Tiley ◽  
T. Y. Choi

Multi-wall carbon nanotube (MWCNT)-reinforced nickel composites have been manufactured in a bulk form by using a laser deposition technique, commercially known as the laser engineered net shaping (LENS™) process. These nanocomposites have been characterized in detail by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and high-resolution TEM study has also been conducted on these nanocomposites to characterize the nanotube/metal matrix interface. In addition, the thermal conductivities of Ni/CNT composites deposited by the LENS™ process have been measured by using Fourier Law of conduction in vacuum. The measurement did not show enhancement of thermal properties, which is caused by the inherent formation of voids and carbide formed during the LENS™ process.


Author(s):  
M. G. Burke ◽  
M. N. Gungor ◽  
M. A. Burke

Intermetallic matrix composites are candidates for ultrahigh temperature service when light weight and high temperature strength and stiffness are required. Recent efforts to produce intermetallic matrix composites have focused on the titanium aluminide (TiAl) system with various ceramic reinforcements. In order to optimize the composition and processing of these composites it is necessary to evaluate the range of structures that can be produced in these materials and to identify the characteristics of the optimum structures. Normally, TiAl materials are difficult to process and, thus, examination of a suitable range of structures would not be feasible. However, plasma processing offers a novel method for producing composites from difficult to process component materials. By melting one or more of the component materials in a plasma and controlling deposition onto a cooled substrate, a range of structures can be produced and the method is highly suited to examining experimental composite systems. Moreover, because plasma processing involves rapid melting and very rapid cooling can be induced in the deposited composite, it is expected that processing method can avoid some of the problems, such as interfacial degradation, that are associated with the relatively long time, high temperature exposures that are induced by conventional processing methods.


1988 ◽  
Vol 120 ◽  
Author(s):  
L. Christodoulou ◽  
P. A. Parrish ◽  
C. R. Crowe

AbstractThe advantages of reinforcing metals with ceramic particles to produce metal matrix composites are well known. The behavior of discontinuously reinforced intermetallic compounds, however, has not been extensively studied. Martin Marietta Laboratories has produced a new generation of discontinuously reinforced titanium aluminide composites using a proprietary casting process known as XD™ technology. These new materials possess enhanced properties at room and elevated temperatures and may be cast, extruded, or forged. The effects of matrix composition, reinforcing phase, and thermal mechanical processing on properties have been studied using optical and various electron microscopy and mechanical and physical property measurement techniques to characterize the alloys. To date, most work has been done on a two-phased lamellar Ti-45 a/o Al alloy reinforced with TiB2 ceramic having an equiaxed morphology. Data on temperature dependence of the dynamic Young's modulus, coefficient of thermal expansion, deformation and fracture behavior, and microstructure are presented.


Author(s):  
Thiago Azevedo ◽  
Italo Leite de Camargo ◽  
Johan sebastian Grass Nunez ◽  
Fábio Mariani ◽  
Reginaldo Coelho ◽  
...  

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