The material does not necessarily have to be harder itself, but can effectively exhibit greater strength depending on casting method. I've posted some shit below, but rheocasting should allow for a tighter molecular structure with very high pressure resistance from the pressed-in axles and likely from impact. Also if it does lead to tighter tolerances chances are the axles are pressed in at such a high force that any slip is unlikely. Plus since they aren't a single piece there isn't a risk of traditional axle slip.
Slightly technical paper:
https://www.sciencedirect.com/topics/engineering/rheocasting
Slightly technical article: https://www.spotlightmetal.com/the-commercial-breakthrough-of-rheocasting-a-801820/
Wikipedia's benefits of rheocasting, I've bolded the parts relevant to Lurpiv trucks:
Complex parts produced net shape
Porosity free
Reduced shrinkage
Excellent mechanical performance
Pressure tightness
Tight tolerances
Thin walls
Heat treatable (T4/T5/T6)
Good surface finish[/li]
[li][/li]
[/list]
"Other advantages include ease of automation, consistency, production rates equal to or better than die casting rates, no air entrapment, low shrinkage rates, and uniform microstructure"
See, now this is what I find interesting, and raises some questions as to what is aesthetic vs. due to the manufacturing process vs. improvement:
Is the shape dictated by the rheocasting or an aesthetic decision made possible by the process? I don't give a crap about the T hanger look and wonder how light/strong something with a more standard braced V design would be.
Is the 2 piece axle thing for strength, or weight or...?
And if you're like me and get a huge heelside groove, are you gonna hit that fat part of the axle too soon?
The kingpin/baseplate design is the most interesting feature, I think. In the x-ray pix, it looks like there are ample threads past the nut - enough that it looks like the plate may be extra thick to accommodate them. Is the KP an off-the-shelf shoulder bolt? Seems possible that using an existing part and putting a little extra material in the baseplate might make $ sense.
Mostly, the improvement to "because we can" ratio on these trucks is too uncertain for my pea sized brain to grasp. The T hanger design, the most noticeable outward characteristic & having no visible advantage, coming relatively soon after ace's (a another atavistic T'er) massive upselling of really standard truck makes me a skeptic. Of course, they're not making a size I ride yet and I'm prolly not the target market anyway.