本文選題：灰鑄鐵　切入點：氮化鈦顆粒　出處：《材料熱處理學(xué)報》2015年12期

【摘要】：為了研究灰鑄鐵中TiN顆粒形成與長大規(guī)律及其組織特征,采用顯微組織及熱力學(xué)計算研究某汽車發(fā)動機缸體鑄件中TiN顆粒形態(tài)、尺寸及分布,并對TiN形成與長大機理進行了分析討論。結(jié)果表明,因回爐料中TiN的遺傳性形成的TiN顆粒尺寸相對較大,超過20μm;從鑄鐵熔體中結(jié)晶的TiN顆粒尺寸為4~8μm;從過冷奧氏體中析出的TiN顆粒尺寸相對較小為1~2μm。熱力學(xué)計算表明,TiN結(jié)晶取決于鑄鐵熔體中[%Ti]·[%N]的溶度積,當(dāng)鑄鐵熔體中[Ti]在0.045%附近([%Ti]·[%N]=2.47×10~(-4))時,鑄鐵熔體過冷到1368℃,即開始結(jié)晶TiN。由于TiN與MnS晶體結(jié)構(gòu)相同,點陣常數(shù)相近,過冷鑄鐵熔體中TiN多以MnS為基底非自發(fā)成核長大。
[Abstract]:In order to study the formation, growth and microstructure of TiN particles in gray cast iron, the morphology, size and distribution of TiN particles in an automobile engine cylinder block casting were studied by means of microstructure and thermodynamics calculation. The mechanism of formation and growth of TiN was analyzed and discussed. The results showed that the size of TiN particles was relatively large due to the heredity of TiN in recirculating charge. The size of TiN particles crystallized from cast iron melts is 4 ~ 8 渭 m, and that of TiN particles precipitated from undercooled austenite is relatively small to 1 ~ 2 渭 m. Thermodynamic calculations show that the crystallization of tin depends on the solubility product of [Ti] [N] in cast iron melts. When [Ti] in cast iron melts is near 0.045% ([Ti] [N] = 2.47 脳 10 ~ (-4) C), the supercooled cast iron melts begin to crystallize at 1368 鈩，

本文編號：1694347