The BR20 and CR42 that came down in Suffolk during the Battle of Britain were scientifically examined by the RAE Farnborough. The BR 20 was the recipient of 18 reports (EA 31 / 1 – 18) of which only two covered Metallurgical examination of parts. Report EA 31/16 (RAE Materials Dept Report M6385) covered parts of the airscrew assembly whilst EA31/17 (M6538) covered parts of the Fiat A80 RC 41 engine.
The CR42 was subjected to 7 RAE reports with no metallurgical tests other than an examination of the fuels and oil tanks.

This information comes from another RAE report (Library bibliography 312 Published March 1969 Catalogue of Enemy Aircraft Reports)

And before JWP asks there are no identifiable RAE reports on the metallurgy of the Junkers or VDM props, but there are some reports containing nice photos of the component parts.