Airlines are slashing orders for Airbus and Boeing passenger planes as the travel and tourism industry has collapsed. In response, carriers have had to quickly reduce operating capacity by ground fleets of planes until passenger volumes recover. 

Boeing CEO Dave Calhoun recently warned it could take 2-3 years for air travel growth to return to pre-corona levels, adding that long term growth trends could take much longer. 

With reduced flights and declining orders for new planes, demand for cobalt used in jet turbine blades is expected to slump in the back half of the year. 

"The harsh high temperature and pressure environments of the jet engine necessitates regular replacement of turbine blades," CRU analyst George Heppel told Reuters. "But planes are grounded, turbine blades aren't being used and don't need replacing."