Institute of Aeronautical Materials (BIAM)
Bejing 100095, China
In Biam, it has pqaid attention to the cast superalloys. For the past 40 years, 25 cast superalloys, about a half of chinese cast superalloys, have been developed for making blades, vanes ande other high temperature parts of various aero-engines.The BIAM's alloys normally appeared later about 10 year than the foreign alloys at same generation, but the main properties canreach to ones of foreign alloys, moreover some alloys have characteristic of low density and low cost.
The conventional cast superalloy K403 developed in the early 1960's. It was used as blades and guide vanes in 16 type engines and is one of the widest application alloys in China. In the directionally solidified alloys, DZ4 and DZ22 are representative.. The Hf-free DS superalloy DZ4 is the first DS alloy utilized to the serving aero-engine in China due to its high creep-rupture strength and excellent castability. Single crystal superalloy DD3 is the first generation SC alloy. The evaluated results obtained by both sides of BIAM andPWA proved that its high temperature creep-rupture strength was comparable with famous SC alloy PWA 1480, but there are no expensive elements such as Hf, Tam and Re in DD3 alloy. Moreover its density is only 8.15 g/cm3. This alloy is also the first SC alloy put into production in small quantity in our country. DD6 alloy is the second generation SC superalloy containing 2wt.% Re and provides an approximate 30 C improved creep strength relative to first generation DD3 alloy. At present, This alloy has been selected as HP turbine blades in an advanced aero-engine. The directionally solidified Ni3Al base alloy IC6 containing about 85vol.% Gamma' phase has been recently developed in BIAM for engine blades and vanes operating in the temperature range of 1000-1150C. The cost of the alloy is only 40% of PWA1422 and density reduce 7%. The 8 sets turbine vanes (-400 pieces) were produced by this alloy and completed 42h flying test.
during development of alloys, in order to solve the urgent problems in research and production, a series of research work has been done. It covers the following fields: 'ductilty valley' of superalloys at intermediate temperature, effect of element Hf in CC and DS superalloys, formation and furactur of mu phase, relationship between solidified behavior and castability, incipient melting and its control, bonding of SC superalloys, recrystalization of DS and SC suprealloys and effect of rare-earth elements on superalloys.
In the future, the requirement of high temperature, high strength, low density and low cost is still driving force for development of cast superalloys. The key considerations are to improve the performance of existing alloys, to use new generation alloys to engines, to pay more attention to the cost and environment factors and to solve the large amount of technical problems during scale industry production.