In the late 1950s the U.S Air Force searched for a fuel with similar characteristics to jet fuel but with higher energy density allowing longer flight range for bombers. In 1947 the British had discovered elemental boron to be the ideal replacement to carbon as it had lower bond dissociation energy leading to higher heat of combustion, 68 MJ/kg vs 42.8 MJ/kg for JP-4.$^1$
Pentaborane B5H11 was found to be unstable, so B5H9 was used as it possessed much better stability. Pentaborane B5H9 performed well in turbojet combustors but it was found that emissions of solid boron particles upon combustion caused severe erosion of the high pressure turbine blades. Is it possible that new ceramic matrix composite turbines blade with higher density and abrasion resistance could solve this problem?
$^1$ Frietas 2018 handbook of energy density Robert A. Freitas Jr., “Energy Density,” IMM Report.