Ken,

It will adhere to both types of metal.

Surface prep is one key. Scuff sand the full surfaces and then clean with a residue-free solvent such as lacquer thinner. Do not touch the surfaces after prep. To get an idea of clean, try cleaning an aluminum sheet. Scuff it with red ScotchBrite and Ajax cleanser. Then rinse it off with tap water. If the water sheets off, you have achieved a "water-break-free" clean surface. Don't let aluminum sit around long after cleaning it or you can start over.

Just as important to a strong structural bond is optimum joint geometry. You gave no hint as to your joint design. You need surface area. You do not want peel. If one of the pieces is flexible, especially watch out for edge propagation failures.

You are bonding dissimilar metals. This is done all the time, but it means that if cured at say, 70F, if the part is required to operate at higher temperature, there will be stress introduced across the bond line. Since the adhesive can only take so much stress, any static stresses (thermal or otherwise) will subtract from the strength you are counting on for the working strength. A slightly thicker bond line helps with dissimilar metals under thermal expansion. JB Weld is a kind of modified epoxy that is more tolerant of this. Generally, with filled epoxy, you should be looking for a bond line of .008 to .010". I don't know how fine they grind their filler, but it is likely much less than this, so heavy clamping may result in a too-thin bond line.

Remember that epoxy strength goes down rapidly with increasing temperature. That does not sound like an issue for your landing gear. It turns out that JB weld compares quite well against some much more expensive aerospace bonding materials. I ran the tests just for fun, and was quite surprised at the results.

The bond will be stronger if you post cure it. I would suggest something like 125F for a few hours right after it has set up. People do not realize that nearly all epoxies are not fully curable at room temperature. That is strength you are just giving away....

For model applications, do not file or sand on the bond material to "clean it up" after the joint is done if it is to be around fuel or oil. The epoxy cures with a skin that is highly resistant, but if you take that skin off, the bond will deteriorate much faster under direct exposure. This info comes from rebuilding venturis and other engine repairs. I would imagine that a landing gear will be oil-soaked unless you are flying this plane on electric.

If you break a good bond joint apart, you can see two types of failures intermixed:  cohesive failures and adhesive failures. Adhesive failure is when all the glue comes off the part clean. It failed at the surface. So the surface prep was inadequate, and if not from poor cleaning, then the joint may need a bond primer for that material. (Stainless steels are like this, as are other materials.) A cohesive failure means that the glue stuck to both sides, but failed inside itself. Either the bondline was too thick, or the adhesive lacks strength for what you are trying to do. A crack that starts on one side and starts progressing tells you that your joint design is not good enough. Consider the loadpath, the flexibility of the parts, and whether you have enough bondline to achieve the joint strength you need.
 
You may also need a hybrid approach if we are talking about a lap joint of music wire and some aluminum strip. That is an inherently bad geometry because there is almost no contact area of optimum joint thickness.

If you have a sketch, there may be some specifics that would help the results.

Good luck!

Dave

Structural epoxy glue such as T88 will give a much better bond than JB Weld.

JB Weld doesn't seem to have great shear strength.  However, for moderate stress, just fine. 

I used JB Weld to fix a crack in the top of my Toyota radiator.  Subject to moderate pressure when hot, so I'm sure the sheet metal flexes some.  However, it's still holding after 10 years.