摘要
以特制的无机盐玻璃70%Na_2SiO_3+17.7%Na_2B_4O_7+12.3%B_2O_3作为净化剂,去除液态Ni-32.5%Sn 共晶合金中的异质晶核,使过冷度达302K(0.215T_E)。采用高速摄影及快速红外测温技术研究了深过冷熔体的快速凝固行为。发现尽管过冷度超过了以往认为的均质形核临界过冷度0.2T_m,但是 Ni-32.5%Sn 共晶合金仍然优先发生界面异质形核,再辉过程中瞬时凝固速度最大可达784mm/s。
Ni-32.5%Sn eutectic alloy has been undercooled by up to 302K(0.215T_E)throughdenucleating with a special boron-silicate glass 70% Na_2SiO_3+17.7% Na_2B_4O_7+12.3%B_2O_3.Its rapidsolidification behaviour during recalescence was studied by means of high speed cinematography andrapid infrared pyrometry,It is found that interface heterogeneous nucleation takes place in preferenceto homogeneous nucleation even at an undercooling above the previously accepted critical undercool-ing 0.2T_mfor homogeneous nucleation,and that the transient solidification velocity attains 784mm/s.
基金
国家自然科学基金
5870066
关键词
凝固
摄影
液态金属
undercooling
rapid solidification
crystal nucleation and growth
eutectic alloy
high speed cinematography
