Most likely some sort of 'high impact' plastic. Saw builders today are employing more and more plastic parts in as much as they are less expensive to produce, are lighter and structurally are just as good strength wise as alloy.
If you want alloy parts, better be buying an older saw and most likely rebuilding it or have the OP rebuild it for you as again, you won't find very many 'modern' saws devoid of plastic parts today. Why I like my old Stihl's alloy parts but then again repairing busted alloy parts (especially crankcases) entails some rather sophisticated welding techniques. Welding aluminum or magnesium alloys require TIG welding and extreme pre prep and the filler rod is super expensive as well. Just TIG welded a Dolmar with a cracked oil tank that was peeing bar oil everywhere. I had to complete disassemble the saw, carefully prep the casting to remove any and all traces of bar oil, I had to hot tank degrease the case and then clean it again with non chlorinated brake cleaner, numerous times, pressure dry it and then weld it and the filler rod was insanely expensive as well plus I had to run straight argon on the TIG welder, bevel the crack in the case and weld it on the inside as well as the outside and take special precautions when welding it because magnesium alloy's are flammable if over heated, especially any grinding swarf. I returned the saw to the owner not assembled as I don't do that sort of thing (rebuild-reassemble) saws anyway. TIG welding aluminum or aluminum-magnesium alloys are difficult to put it mildly and only reason I did it was because it was for a friend but I still charged him for the filler rod and yes, the external weld looks 'cobbly' but the Dolmar is his baby so I did it for him.
Die cast alloys always look nice until they have to be repaired, then they don't look so pretty. Have no idea how he cracked the case in front and didn't ask either. All I know was, it was peeing bar oil everywhere and making a huge mess. Don't now or I assume it don't now as again I returned it to him in a box, not assembled.
The issue with repairing ANY failed part or die casting that has been subject to oil contamination is all in the prep. You absolutely MUST remove all traces of any lubricant or grease to effectuate a sound and non porous weld. That applies to even mild steel. That is what takes time and patience. After I welded I dye scanned the weld to make sure it was sound and had no leaks. Not something an ordinary 'Joe' can do successfully in their home shop either. I own the equipment including the hot tank degreaser.
