Precipitation of Aluminium Nitride during Recrystallization of α-Iron

Abstract

An investigation has beell made 011 the preci/Jitatioll oj A 1 N in vaCllUIII melted iron wires containing 0.003, 0.036, and 0.012 wtO ° A I, solutiontreated at 1 200"e, cold-reduced to 10°o, and isothermally annealed in the range 500' to 100oe . The behaviour oj A I N in a-iron during annealing was JoLLowed by low frequency internal Jriction measurement . By separating the observed Snoek peaks ill to those oj carbon and nitrogen, the amounts oj carbon and nitrogen dissolved in solution were determined. The results obtained were summarized as JoLLows : (I ) In Fe0 .003 wt O,o A I, Ilitrided or carburized prior to the solutiontreatment, the amount oj dissolved nitrogen u:as increased during isothemial anllealing at 600 0 e aJter cold reductioll, whereas the amoullt q! dissolved carbon decreased to the solubility limil. (2) Some difference was seen in the IJrocess oj AIN precil)itatioll during isothermal annealing between Fc0.036 wt°;" A I-O.006 wt 0" 1':, in which the A I N IJarticies were completely dissolved by a solutioll-treatment at 1 200 ' e, and FeO.012 wt % AIO.028 wt O oN, in which some oj the AIN j)articies remained undissolved. AIN precipitation ill both cases occurred during the recovery and in the early stage oj recrystaLLization at 600' e, and the reClystaLLization was retarded. (3) 111 Fc0.012 wt% AlO.028 wt%N annealed at 100De, the recrystaLLization was comlJleted bifore A I N preci/Jitation started. Hou'ever, a preheat-treatment oj Jor 20 hr at soooe given l;rior to 100ee allllealillg did significalltly affect the recrystaLLization l;rocess by promoting A I N Im cipitation and decreasing the recrystaLLi:::atioll rate .