Impeller with widened blades

A rotary impeller assembly is for a fluid machine and includes a support member having an outer surface and blades connected to the support member. Each blade includes first and second integral portions, the blade first portion having a first thickness and being spaced from the base surface and the blade second portion is disposed against the support member outer surface and has a second thickness. The second thickness is substantially greater than the first thickness such that the blade has greater stiffness proximal to the support and a lesser stiffness generally distal from the support. Preferably, the blades are connected with the support welds between each blade sidewall and the support member. Further, each blade first portion is sized such that the blade first thickness is maintained in a significant area of the blade spaced from the weld(s) so as to allow blade flexure away from the weld.