Turbine blades, not fan blades. The single crystal metallurgy is to avoid high-temperature creep (i.e. slow deformation over time under an applied load), which

Turbine blades, not fan blades. The single crystal metallurgy is to avoid high-temperature creep (i.e. slow deformation over time under an applied load), which is a life-limiting factor in turbine blades. Especially the first row or two which see the highest temperatures.