The use of single crystal blades

THE USE OF SINGLE‐CRYSTAL BLADES in gas‐turbine engines have considerable advantages over conventionally cast blades since they do not possess grain boundaries which in conventional castings are weak points along which premature damage can occur. Because grain boundary voids and vacancies are almost entirely eliminated, single‐crystal blades exhibit more uniform property characteristics, higher thermal fatigue resistance (even at temperatures close to the melting point) and hence superior reliability. At extremely high temperatures they can operate for about four times as long as conventionally cast blades whilst at intermediate temperatures (800° to 900°C) they can operate for eight to ten times as long.