快速凝固Al94Ti4C2合金的显微组织和相结构分析

 研究了快速凝固 Al94Ti4C2 (at% )合金的显微组织和相结构特征。常规金属型铸态组织由分布于 α-Al基体中的片状 Al3Ti和以团簇形式存在的尺寸为 0 .3～ 1 μm的 Ti5C4 颗粒组成。经快速凝固以后 ,Ti5C4 分散为 2 0～ 40 nm的颗粒 ,接近连续地排列于α-Al晶粒边界 ;而 Al3Ti的形成受到抑制并为一有序 LI2 结构的亚稳相 (～ Al4 Ti)所替代 ,该相的晶格常数为 a0 ≈ 0 .40 4 nm,呈单个颗粒分居于每个 α-Al晶粒内 ,同 α-Al之间保持完全共格关系。以此为基础 ,对凝固过程特别是 Ti5C4 形成机制进行了分析和探讨

ANALYSIS OF MICROSTRUCTURE AND INTERMETALLIC PHASES IN A RAPIDLY SOLIDIFIED AL94Ti4C2 ALLOY

Intermetallic phases and microstructures of a rapidly solidified Al94Ti4C2(at%)alloy have been investigated. The DC casting microstructure comprises α Al, sheet like Al 3Ti and 0 3~1μm sized Ti 5C 4 particles appearing in the form of particle clusters. In the rapidly solidified alloy ribbons, the Ti 5C 4 phase disintegrates as fine particles of 20~40nm size, accumulating at and becoming trapped along the α Al grain boundaries, while Al 3Ti is replaced by an ordered LI 2 crystal structure (a 0≈0 404nm)metastable phase(~Al 4Ti),which is distributed in the α Al grains and retains a coherent lattice relationship with α Al matrix. Moreover, the formation mechanism of the intermetallic phase is discussed.