In situ synthesis of TiC-Al (Ti) nanocomposite powders by thermal plasma technology
- PDF / 445,331 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 78 Downloads / 133 Views
INTRODUCTION
DISCONTINUOUSLY reinforced metal matrix composites (DMMCs) as a novel class of materials have been one of the major innovations in materials in the past 25 years, and they are already attracting the attention of materials producers and end users.[1,2] Many critical applications of DMMCs have now been implemented in the aerospace, automotive, and transportation industries, as well as the electronics and recreational fields.[2–6] However, largetonnage applications of DMMCs as advanced structural materials in industries have not been considered sufficiently cost-effective.[2] The challenge for future technologies is to improve the quality/cost ratio, thus making DMMCs highly competitive in industries.[2–5] As Kevorkijian noted, DMMCs’ drawbacks mainly center on reduced ductility and toughness and the extra cost of reinforcement over metallic materials.[2] It is well known that significant improvement in the mechanical properties of DMMCs will depend on significant reduction in the size of the ceramic reinforcement,[2–6] a further increase in the volume fraction of ceramic phase contained in the metallic matrix, and a strong interfacial bonding between the matrix and the reinforcement. Significant reduction in the cost of DMMC production will depend on simplifying the processing technology and steps of manufacturing DMMCs and avoiding the extra cost of reinforcements.[6–9] The scientific awareness has inspired material scientists to develop novel economic processing techniques for the manufacture of DMMCs, including in situ processing techniques of DMMCs and nanocomposite powders. The in situ processing technique of DMMCs follows conventional routes, except that reinforcements are directly formed in the matrix melts. The technique not only reduces the processing steps and cost, but also avoids the introduction of contaminations on the reinforcement surface and thus improves the compatibility and LIRONG TONG, Graduate Student, and RAMANA G. REDDY, ACIPCO Professor, are with the Department of Metallurgical and Materials Engineering, The University of Alabama, Tuscaloosa, AL 35487. Contact e-mail: [email protected] Manuscript submitted April 25, 2005. METALLURGICAL AND MATERIALS TRANSACTIONS B
thermodynamic stability of reinforcements in metal matrix.[6,7] Also, the size of the ceramic reinforcement is normally several microns. In situ processing techniques of nanocomposite powders not only have the advantages of in situ processing techniques of DMMCs, but also further reduce the size of the ceramic reinforcement to the nanometer level and possibly achieve uniform distribution of reinforcing particles in matrix. Thermal plasma processing (TPP) is a novel technology being developed for the processing of advanced materials.[6–13] The TPP technique provides a very high processing temperature (more than 10,000 °C), where all the materials would be in a monatomic gaseous state, and very high quenching rates that allow direct nucleation from the supersaturated gases to form nanopowder. The technique is very desirable
Data Loading...
