块体Pd_(82)Si_(18)非晶合金的制备及晶化行为研究

Formation of Pd_(82) Si_(18) bulk metallic glass and its crystallization

采用玻璃包覆 +水淬技术制备了块体Pd82 Si1 8非晶合金 .实验结果表明 ,净化对该熔体的非晶形成能力有很大的影响 .通过对深过冷Pd82 Si1 8合金的凝固行为研究发现 ,当过冷度大于 1 90K时 ,过冷熔体会出现液相分离现象 ,热力学分析表明这将降低该过冷熔体的非晶形成能力 .该非晶的晶化实验结果显示 ,与旋铸法制备的Pd82 Si1 8非晶条带不同 ,块体非晶的晶化过程中出现两个放热峰 ,同时玻璃转变温度、晶化温度、过冷液相区都有相应的变化 .通过分析可知Pd82 Si1

Bulk amorphous Pd 82 Si 18 alloy with a diameter of 8?mm was prepared by water quenching the molten alloy with flux medium in a quartz tube. Experimental results showed purifying melt had effect on glass formationability of molten alloy. Solidification behavior of supercooled Pd 82 Si 18 molten alloys was investigated. When undercooling Δ T >190?K, undercooled molten alloy came into liquid phase separation (LPS). According to thermodynamics, LPS decreased glass formationability of molten alloy. There was difference between amorphous strip prepared by spinning melt and bulk amorphous in crystallization of amorphous alloys. Compared with the single exdothermic peak in amorphous strip, bulk amorphous alloys appeared two exdothermic peak. There were some changes in glass transition temperature T g, crystallization temperature T x, undercooling liquid phase region(Δ T=T x- T g). Crystallization course was discussed in reference to cooling rate of preparation of Pd 82 Si 18 amorphous alloys.