document: Gamma titanium aluminides are a family of low density, high performance alloys with the potential to replace current Ni-base superalloys used in the production of aero-engine components. Investment casting is one of the most economical methods to produce titanium and titanium aluminide alloy products, increasing the components' integrity and mechanical properties, whilst reducing material waste and machining cost [1]. Titanium aluminides are difficult to process mainly due to the low fluidity of the TiAl alloy around its melting temperature [2]. Due to the high affinity of elements such as oxygen, nitrogen etc., titanium and its alloys can easily interact with mould materials during the investment casting process, resulting in an interaction hardened layer being generated at the metal surface [3,4]. This hardened layer contains a large amount of dissolved oxygen, and it is very brittle and susceptible to crack generation and propagation [5].
extractive_keyphrases: alloys casting process crack generation and propagation dissolved oxygen elements gamma titanium aluminides hardened layer investment casting metal surface mould materials nitrogen oxygen produce titanium and titanium aluminide alloy products the components tial alloy titanium
abstractive_keyphrases: aero-engine components interaction hardened layer ni-base superalloys production of aero-engine components titanium aluminide alloy titanium aluminides