The composition of "standard" commercially available terfenol-d is terbium (Tb) 0.3, dysprosium (Dy) 0.7, and iron (Fe) 1.92. Mass density is 9,250 kg/m^3. By weight percent, terfenol-d contains

• Terbium -- 17.7%
  
  
• Dysprosium -- 42.3%
  
  
• Iron -- Balance

Terfenol-d is inert to direct contact with liquids such as non-ionic hydrocarbons.