The 1N4148 virtually replaced the venerable 1N914 signal switching diode in most logic applications. I have been using it since the 1970s and have never found fault using it to replace the 1N914. However, both diodes are fast signal diodes, not power diodes. You need to be aware of this limitation when dumping the energy stored in large inductive loads. Relays that mount on printed circuit boards typically DO NOT exhibit large inductive loads, but external, high-amperage, contactors typically DO. Such contactors are also not typically rapidly cycled, so average amount of energy storage in their magnetic fields is small. It is with high inductance, high coil current, rapid and frequent ON/OFF cycling contactors that the designer must be careful when considering to place a diode across the actuator coil. A considerable current pulse will flow through the diode when the contactor coil is de-energized, so make sure the diode is up to the task of conducting this current pulse.
Another element of design that is often neglected, or not considered at all, is the drop-out time after the actuator coil circuit is open-circuited. Because there is an inductance and a current involved, simply creating an "open circuit" by, say, turning a transistor off, does not mean the current drops instantaneously to zero. It cannot, nor does it. I will not go into the details here, but essentially placing a diode across the coil slows down the decay of current and increases the drop-out time,
