Optimum glass formation at off-eutectic composition and its relation to skewed eutectic coupled zone in the La based La–Al–(Cu,Ni) pseudo ternary system
✍ Scribed by H Tan; Y Zhang; D Ma; Y.P Feng; Y Li
- Publisher
- Elsevier Science
- Year
- 2003
- Tongue
- English
- Weight
- 782 KB
- Volume
- 51
- Category
- Article
- ISSN
- 1359-6454
No coin nor oath required. For personal study only.
✦ Synopsis
Glass formation and its relation to the dendritic and eutectic growth has been investigated for the La 100Ϫx [Al 0.412 (Cu,Ni) 0.588 ] x (x = 30-56.3) and La 86Ϫy Al 14 (Cu,Ni) y (y = 16-29) alloy systems. The experimental results show that in the La-rich pseudo ternary La-Al-(Cu,Ni) system, optimum glass formation actually occurs at an offeutectic composition. A nearly fully amorphous rod with 12 mm in diameter can be obtained at an off-eutectic composition near La 62 Al 15.7 (Cu,Ni) 22.3 , while only a 1.5 mm diameter rod can be obtained fully amorphous for the eutectic alloy La 66 Al 14 (Cu,Ni) 20 . A strong dependence of GFA on the composition is observed for these alloys. In addition, formation of a composite (i.e. αLa dendrite reinforced glass matrix) in 12 mm diameter cast rods is observed over a wide range of composition, including the eutectic composition. It has been found that the GFA does not correlate well with the extent of the undercooled liquid region (⌬T x ) and is not even closely related to the reduced glass transition temperature (T rg ). These unusual observations in glass formation and its relation to the skewed eutectic coupled zone have been explained in terms of the competition between the growth of crystalline phases (i.e. eutectic and dendritic phases) and the formation of the amorphous phase.