Microstructure and sliding-wear behavior of tungsten-reinforced W-Ni-Si metal-silicide in-situ composites
- PDF / 1,426,107 Bytes
- 11 Pages / 606.24 x 786 pts Page_size
- 50 Downloads / 272 Views
8/8/03
5:14 PM
Page 2005
Microstructure and Sliding-Wear Behavior of TungstenReinforced W-Ni-Si Metal-Silicide In-Situ Composites H.M. WANG, D.Y. LUAN, and L.X. CAI W-Ni-Si metal-silicide-matrix in-situ composites reinforced by tungsten primary grains were fabricated using a water-cooled copper-mold laser-melting furnace by the LASMELT process. Main constitutional phases of the W/W-Ni-Si in-situ composites are the tungsten primary phase, peritectic W2Ni3Si, and the remaining W2Ni3Si/Ni31Si12 eutectics, depending on the alloy compositions. The sliding-wear resistance of the W/W-Ni-Si intermetallic composites was evaluated at room temperature and 600 °C. Wear mechanisms of the W/W2Ni3Si in-situ composites were discussed based on morphology observations of the worn surface and wear debris. Results show that the W/W-Ni-Si composites have excellent wear resistance under both room- and high-temperature sliding-wear-test conditions, because of the high yield strength and toughness of the tungsten-reinforcing phase and the high hardness and the covalent-dominated intermetallic atomic bonds of the W2Ni3Si and Ni31Si12 metal silicides. Tungsten-reinforcing grains played the dominant role in resisting abrasive-wear attacks of microcutting, plowing, and brittle spalling during the sliding-wear process, while the W2Ni3Si and Ni31Si12 metal silicides are responsible for the excellent adhesive wear resistance.
I. INTRODUCTION
TRANSITION-METAL silicide-based intermetallic alloys (e.g., Mo-Si, Ti-Si, Cr-Si, Nb-Si, Zr-Si and Ni-Si binaries and their multicomponents alloys such as Mo-Ni-Si, Cr-Ni-Si, W-Ni-Si, etc.) represent the largest family of intermetallic compounds having attractive attributes for elevated-temperature mechanical and environmental properties and, hence, are well recognized as a new family of highand/or ultrahigh-temperature candidate structural materials, because of their excellent combinations of high melting point, low density, high elastic modulus, and excellent oxidation resistance.[1–12] From a tribological point of view, these silicidebased intermetallic alloys also have excellent tribological properties (e.g., abrasive and adhesive wear resistance as well as a low coefficient of friction, due to their intrinsic roomand high-temperature high hardness and their unique covalent-dominated intermetallic atomic-bonding characteristics) and are, therefore, a new class of promising advanced wearresistant candidate materials for tribological components working under corrosive and high-temperature hostile service conditions.[13–18] However, like most intermetallic alloys, the existence of intrinsic room-temperature brittleness and lack of adequate strength and creep resistance at elevated temperatures are currently the main obstacles that prevented the materials from industrial applications as either structural or tribological bulk components.[1–10] Compared to binary silicide alloys, multicomponent and multiphase metal-silicide intermetallic alloys (e.g., the W-Ni-Si multiphase intermetallic alloys containing
Data Loading...
