During the H2 protection heat treatment of 1J50 ( Fe-50%Ni ) alloys, to get good soft megnetic performance, the microstructure of 1J50 alloys should be large grain size austinite and the FeNi and FeNi3 phase must be prevented.

Effect of the heat treatment temperature,heat treatment atmosphere,and deformation conditions on the recrystalliza- tion behavior of a directionally solidified superalloy was studied by using differential scanning calorimetry(DSC)and metallo- graphic analysis.

The effects of heat treatment atmosphere on the content of Bi2201 phase in tapes and the current transport capacity are studied using the X-ray diffraction(XRD),superconducting quantum interference device(SQUID) and the four-probe technique.

The result shows that,the phase of 1J50 has changed and the magnetic properties has improved remarkably after heat treatment by H2.

In the paper,the author introduces the functions of nitrogen in heat treatment atmosphere,describes the different nitrogen suppplies and preparing methods,discusses the steadiness of PSA nitrogen preparing equipment and persents that at present,the PSA nitrogen preparing still is a proper nitrogen supply for the Chinese nitrogen based atmosphere heat treatment.