It could very well be, and probably is, but I think more testing would be necessary to make sure. It's just a standard SOT-23 package, so it could be a diode, a transistor, a voltage regulator, or hundreds of other possibilities. If you could verify that the manufacturer of the device in question is NXP, then you can be sure that W70 means it is a BZX84-A11. But unless you can determine without a doubt that it is made by NXP, there is still a chance that it is something different.The OP asked if it was a bzx84-A11, and the code W70 denotes (at least in one usage) a BZX84-B16. I thought there was enough evidence.
In place of the 10K resistor use these resistor values (or approximate values) in turn:I cannot determine for sure about the manufacture, but i can confirm it's a diode, but here's what makes me confuse, if this is an nxp diode, and according to nxp bzx84, then the working range for this series would be from 2.4 to 75v related to marking code, in this picture, the marking code is 04 instead of the w70, and nxp datasheet, 04 would be an 11 volt zener, so it is bzx84-a11, but if i feed this diode with 24v series with 10k resistor, the voltage measured is 16 volt, i compare it with other w70 with marking code is 10, the result is the same, 16 volt. any advise would be appreciated, thanks a lot