Wear behavior of Al-Al 3 Ti composite manufactured by a centrifugal method
- PDF / 1,452,423 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 101 Downloads / 180 Views
I. INTRODUCTION
LOW specific weight and high-temperature strength make titanium-aluminide intermetallic compounds a promising, lightweight structural material for high-temperature applications.[1] Among them, the Al3Ti intermetallic compound is especially promising because of its lower density, higher hardness, and better oxidation resistance. It is anticipated that Al3Ti is even superior to the well-known TiAl intermetallic compound.[2] Several problems, however, such as low ductility and fracture toughness, must be overcome before the material can be used commercially. One solution to overcoming these problems is to disperse Al3Ti particles in the ductile phase.[3] The authors have proposed a centrifugal method as one of the functionally graded material (FGM) fabrication methods.[4–9] Centrifugal force applied to a mixture of molten metal and dispersed material, such as ceramic powder or intermetallic compounds, leads to the formation of a desired composition gradient. Here, the gradient is controlled mainly by the difference in density between the matrix and the dispersed material. In a recent study, Watanabe et al.[8] manufactured AlAl3Ti FGMs using a commercial Al-5mass pct Ti alloy by the centrifugal method. The alloy was heated to a temperature where Al3Ti platelets remain solid in a liquid Al matrix, and a centrifugal force was applied. The solid Al3Ti platelets in the melt were oriented with their platelet planes nearly normal to the radial, centrifugal force, direction. Figure 1 shows the schematic representation of the YOSHIMI WATANABE, Associate Professor, is with the Department of Functional Machinery and Mechanics, Shinshu University, Ueda 3868567, Japan. NOBORU YAMANAKA, Associate Professor, is with the Department of Mechanical Engineering, Miyakonojo National College of Technology, Miyakonojo 885-8567, Japan. YASUYOSHI FUKUI, Professor, is with the Department of Mechanical Engineering, Kagoshima University, Kagoshima 890-0065, Japan. Manuscript submitted October 21, 1998.
METALLURGICAL AND MATERIALS TRANSACTIONS A
arrangement of Al3Ti platelets. From this representation, it can be predicted that the Al-Al3Ti FGM, shown in Figure 1, will have anisotropic mechanical properties. We proposed to measure these properties using a composite specimen machined from the mostly homogeneous part of the FGM. The wear resistance of composites is of interest because of their potential tribological use in internal combustion engines, as brake rotors, and in the study of die wear during the extrusion of metal matrix composites (MMCs).[10] It has been shown that the wear properties are improved remarkably by introducing a hard intermetallic compound into the Al matrix.[11] It has also been demonstrated that, because the bonding strength between intermetallic and matrix is very strong, pulling out is prevented even at high loads.[12] It is expected, therefore, that the Al-Al3Ti composite should exhibit good wear resistance. Of particular interest is the influence of the anisotropically oriented Al3Ti platelets on th
Data Loading...
