Atomic-scale analysis of early-stage precipitation in Ti(Al,Si)(3) alloy
Atomic-scale analysis of early-stage precipitation in Ti(Al,Si)(3) alloy
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Ti(Al,Si)(3)合金早期析出的原子尺度分析
DOI：
10.1016/j.matdes.2017.08.052
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发表时间：
2017
影响因子：
8.4
通讯作者：
Geng Lin
中科院分区：
文献类型：
--
作者：
Zhang Tongtong;Fan Guohua;Wu Hao;Cui Xiping;Huang Meng;Miao Kesong;Geng Lin
采用原位透射电镜（TEM）在原子尺度上研究了Si在Ti (Al, Si) 3合金中加热至800℃再降至室温（RT）的早期析出行为。在早期析出过程中，Ti (Al, Si) 3合金中存在3种类型的纳米颗粒，分别为富硅纳米团簇、Ti 7 Al 5 Si 12相和Ti 5 Si 3相。Ti (Al, Si) 3合金早期析出的析出顺序和取向关系如下：(1)由于Si的偏析，首先在TiAl - 3基体中形成小的富Si纳米团簇，与较大的富Si纳米团簇共存；（ii）达到临界尺寸（20-30 nm）的富硅纳米团簇作为亚稳Ti 7 Al 5 Si 12沉淀的成核位点，OR值为：002 TiAl 3//1¯6 Ti 7 Al 5 Si 12, 1¯10 TiAl 3//115 1¯Ti 7 Al 5 Si 12；然后（iii）由亚稳的Ti 7 Al 5 Si 12在OR: 10¯0 Ti 5 Si 3//001 Ti 7 Al 5 Si 12, 1¯13 Ti 5 Si 3//010 Ti 7 Al 5 Si 12的转变形成Ti 5 Si 3沉淀。
The early-stage precipitation behavior of Si in Ti (Al, Si) 3 alloy heated to 800° C and then down to room temperature (RT) is characterized at the atomic scale by in-situ transmission electron microscope (TEM). Three types of nanoparticles were observed in Ti (Al, Si) 3 alloy during the early-stage precipitation, which contain Si-rich nanoclusters, Ti 7 Al 5 Si 12 precipitates as well as Ti 5 Si 3 precipitates. The precipitation sequence and orientation relationship (OR) for the early-stage precipitation in Ti (Al, Si) 3 alloy are as follows:(i) small Si-rich nanoclusters firstly form in TiAl 3 matrix due to the segregation of Si, coexisting with larger Si-rich nanoclusters;(ii) Si-rich nanoclusters that reach the critical size (20–30 nm) serve as nucleation sites for metastable Ti 7 Al 5 Si 12 precipitates with an OR: 002 TiAl 3//1 1¯ 6 Ti 7 Al 5 Si 12, 1¯ 10 TiAl 3//115 1¯ Ti 7 Al 5 Si 12; and then (iii) the formation of Ti 5 Si 3 precipitates is by transformation of metastable Ti 7 Al 5 Si 12 with an OR: 10 1¯ 0 Ti 5 Si 3//001 Ti 7 Al 5 Si 12, 1 2¯ 13 Ti 5 Si 3//010 Ti 7 Al 5 Si 12.