Effect of carbon on microstructure and high-temperature strength of NbMoTiSi in situ composites prepared by arc-melting and directional solidification

摘要: Abstract Improvement of high-temperature strength Nb–(10–20)Mo–22Ti–18Si alloys by adding carbon and directional solidification technique has been investigated. Vickers hardness HV compressive at 1470 1670 K were examined. The as-cast specimen without C composes Nb solid solution (Nb SS ) (Nb,Mo,Ti) 5 Si 3 silicide, while (Nb,Ti)C carbide obviously appears when contain more than 2.4 mol% carbon. amount silicide phases increases with increasing content. directionally solidified samples have the same as ones show coarse microstructure slightly oriented to direction growth. A small addition lowers both K, where corresponds appearance phase. By 4.8 carbon, however, , 0.2% yield ( σ 0.2 maximum max tend increase. higher work hardening rate corresponding 10 Mo sample is weakened addition, but a considerable improvement in elevated temperatures can be predicted added 20 material. sliding debonding /silicide interfaces dominant damage temperatures.