What is a "fast 2A type" diode?
The application example (on page 8) which you're looking at shows the diodes connected to an L298N driver, which is distinct from the L297.  Here's is the datasheet you want to look at.

...Which shows that the L298N is just a generic motor driver.  The purpose of the diodes is to prevent the inductance from the motor windings from generating voltages which will destroy the motor driver.  

The 1N4001 is a standard recovery (not fast) diode rated at 1A of continuous current.  Thus, it does not fit the datasheet recommendations, so very large currents may be shared by the transistors you're trying to protect, and the beginning of every cycle will admit some overvoltage to those same transistors.  However, it may be adequate if you're just driving a low-power motor.  

If you've got a high powered motor or are concerned about reliability, I'd recommend Schottky diodes like the common 1N5820 series, which will do a great job of protecting the silicon diodes integral to the L298N output transistors.