Plasticity and brittleness of the ordered βo phase in a TNM-TiAl alloy

被引：10

作者：

Molenat, Guy ^{[1
]}

Galy, Benjamin ^{[1
]}

Musi, Michael ^{[2
]}

Toualbi, Louise ^{[3
]}

Thomas, Marc ^{[3
]}

Clemens, Helmut ^{[2
]}

Monchoux, Jean-Philippe ^{[1
]}

Couret, Alain ^{[1
]}

机构：

[1] Univ Toulouse, CNRS, CEMES, F-31055 Toulouse, France

[2] Montan Univ Leoben, Dept Mat Sci, Franz Josef Stra 18, Leoben, Austria

[3] Univ Paris Saclay, ONERA, DMAS, Ave Div Leclerc,BP 72, F-92322 Chatillon, France

来源：

INTERMETALLICS | 2022年 / 151卷

关键词：

Titanium aluminide alloys; Brittleness and ductility; Dislocation structure; Plastic deformation mechanisms; Powder metallurgy; Transmission electron microscopy; OMEGA-RELATED PHASES; IN-SITU; MECHANICAL-PROPERTIES; QUANTITATIVE TEM; PINNING POINTS; TRANSFORMATION; DISLOCATIONS; DEFORMATION; SLIP; MICROSTRUCTURES;

D O I：

10.1016/j.intermet.2022.107653

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

In order to identify the reasons for the brittleness of a TNM-TiAl alloy (Ti51.05Al43.9Nb4Mo0.95B0.1 in at.%), the plastic deformation behaviour of the ordered beta(o) phase is investigated. The corresponding powder was densified by Spark Plasma Sintering to produce a near lamellar microstructure made of gamma/alpha(2) lamellar colonies surrounded by gamma and beta o grains. Then, the room temperature tensile behaviour is studied by carrying out tensile tests and additional in-situ straining experiments in a transmission electron microscope (TEM). The TNM alloy exhibits a limited ductility, with the fracture surface of test specimens showing cleavage facets along lamellar interfaces. In addition, the beta(o) grains contain nano-precipitates of the omega(o) phase and deform plastically by < 111 > super-dislocations dissociated into two superpartial dislocations separated by an antiphase boundary. These dislocations glide in {011} planes and are observed to be localized into pile-ups, which is related to the omega(o) strengthening precipitation within the beta(o) grains. This localised hardening behaviour leads to stress concentration in grain boundaries which is assumed to be responsible for delamination along lamellar interfaces in neighbouring lamellar colonies.

引用

页数：11

共 43 条

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