It is a combination of casting and forging
Squeeze Casting Process: Part One
http://www.keytometals.com/page.aspx?ID=CheckArticle&site=ktn&NM=172
SQueeze Casting - Furture - A Report 2011
http://issinstitute.org.au/wp-content/media/2011/05/ISS-FEL-REPORT-A-IYER-low-res.pdf
Aluminium in Automotive - Casting Processes Manual
http://www.alueurope.eu/wp-content/uploads/2012/01/AAM-Manufacturing-1-Casting-methods.pdf