Y. Yuan, J. Pan/Journal of Crystal Growth 193(1998)585-591 eutectic liquid phase will be formed to initiate the As shown in Fig. 6, the morphologies of the TiC growth of TiC whiskers [10]. Therefore, a little deposits are often different in different locations of amount of whiskers deposited at the high C/Ti may the nickel substrate. According to the morphology be due to the deficiency of titanium, resulting from variation of whiskers deposited on nickel, from the reduction of TiCl4 with H,, rather than excess- bottom to top the inner surface of the nickel sub- ive carbon to form this Ni-Ti eutectic liquid phase. strate cylinder is divided into three sections, I, Il, When the C/Ti ratio is approximate to or less than Ill, respectively. Three distinctive morphologies are 1, TiC whiskers will almost not form due to insuffi- observed: (1)Type A: Whiskers from location I of cient amount of carbon. Instead, titanium will react the substrate are generally thick(0. 1-1.0 um), long with the nickel substrate to form microcrystals of (0.05-2.0 mm), straight and smooth, as shown in Ni-Ti binary eutectic alloy with low melting point. Fig 6a. The quality TiC whiskers with a high yield The optimum value of the C/Ti is about 1.7 in this are obtained in this location.(2)Type B: Whiskers experiment from location II are thin (0.02-0.5 um), short m 2μm ig. 6. Three types of TiC whiskers obtained at different locations of the nickel substrate: (a)Type A, (b) Type B, (c) Type C.Fig. 6. Three types of TiC whiskers obtained at different locations of the nickel substrate: (a) Type A, (b) Type B, (c) Type C. eutectic liquid phase will be formed to initiate the growth of TiC whiskers [10]. Therefore, a little amount of whiskers deposited at the high C/Ti may be due to the deficiency of titanium, resulting from the reduction of TiCl4 with H2 , rather than excess￾ive carbon to form this Ni—Ti eutectic liquid phase. When the C/Ti ratio is approximate to or less than 1, TiC whiskers will almost not form due to insuffi- cient amount of carbon. Instead, titanium will react with the nickel substrate to form microcrystals of Ni—Ti binary eutectic alloy with low melting point. The optimum value of the C/Ti is about 1.7 in this experiment. As shown in Fig. 6, the morphologies of the TiC deposits are often different in different locations of the nickel substrate. According to the morphology variation of whiskers deposited on nickel, from bottom to top, the inner surface of the nickel sub￾strate cylinder is divided into three sections, I, II, III, respectively. Three distinctive morphologies are observed: (1) Type A: Whiskers from location I of the substrate are generally thick (0.1—1.0 lm), long (0.05—2.0 mm), straight and smooth, as shown in Fig. 6a. The quality TiC whiskers with a high yield are obtained in this location. (2) Type B: Whiskers from location II are thin (0.02—0.5 lm), short Y. Yuan, J. Pan / Journal of Crystal Growth 193 (1998) 585–591 589