Crystallographic orientation relationships and interfacial structures between reinforcement and matrix phases in an in situ (Ti, Nb)B/Ti2AlNb composite

作者：Zhang, Ningbo; Han, Xiuli^*; Sun, Dongli; Liu, Hao; Xue, Wei; Ju, Boyu; Wu, Gaohui

来源：Applied Surface Science, 2021, 542: 148592.

DOI：10.1016/j.apsusc.2020.148592

• Orientation relationships
• Interfacial structures
• Metal matrix composites
• Ti2AlNb
• First-principles calculations

High-performance (Ti, Nb)B/Ti2AlNb composites are promising high-temperature structural materials for the new generation of aerospace engines. The interfaces between the (Ti, Nb)B reinforcement and matrix phases (i.e. O-Ti2AlNb, alpha(2)-Ti3Al and B2 phases) affect the mechanical properties of the composites largely. In this study, the properties of the interfaces were systematically revealed after fabricating a (Ti, Nb)B/Ti2AlNb composite by low-energy ball-milling and spark plasma sintering (SPS). A high-resolution transmission electron microscopy (HRTEM) was adopted to evaluate the crystallographic orientation relationships (ORs) and interfacial structures. (Ti, Nb)B maintains three coherent interfaces with the matrix, and the preferred ORs between them can be expressed as [1 1 (2) over bar 0](alpha 2)//[0 1 0]((Ti, Nb)B) and ((1) over bar 100)(alpha 2)/(1 0 0)((Ti, Nb)B); [1 (1) over bar 0](O)/[0 1 0]((Ti, Nb)B) and (1 1 0)(O)// (1 0 0 )((Ti, Nb)B); ((1) over bar 1 1)(alpha 2)/[010] ((Ti, Nb)B) and ((1) over bar 1 2)(B2)//(1 0 0 )((Ti, Nb)B). The results of first-principles calculations indicated that the ((1) over bar 1 0 0)(alpha 2)/(1 0 0)((Ti, Nb)B) interface possesses a higher bonding strength compared with the (1 1 0)(O)/(1 0 0)((Ti, Nb)B) and ((1) over bar 1 2 )(B2)/(1 0 0)((Ti, Nb)B) interfaces, and the (Ti, Nb)B reinforcement and the matrix are bonded through strong ionic bonds and weak covalent bonds. Moreover, based on Bramfitt's lattice mismatch theory, it was found that the (Ti, Nb)B reinforcement acts as an effective substrate in promoting the heterogeneous nucleation and preferred precipitation of the alpha(2) phase. Suppressing the brittle alpha(2) precipitate around the reinforcement improves the ductility of the composite obviously.

• 单位
  harbin inst technol