本文用衍射仪内标法测定了氧化层的残余应力,研究了稀土元素对Fe-Cr-Al合金在1200℃和1350℃氧化时氧化层残余应力的影响,结果表明,氧化层都存在残余压应力,且稀土元素有明显的影响,不加稀土的A合金σ<100 kgf/mm~2,加(La+Ce)的B合金σ>200kgf/mm~2,加Y的C合金σ>300kgf/mm~2. 若以〔P〕_A=P_(0001)+P_(0118)+P_(1129)+P_(10110)的织构系数值表示氧化层的择优取向的程度,发现氧化层的择优取向程度与粘附性有一定的关系,〔P〕_A>6.5的氧化层不发生剥落,〔P〕_A<6.5的氧化层发生剥落,稀土元素增强氧化层的择优取向程度是它改善氧化层粘附性的原因之一.
The residual stress of oxide scale formed at 1200 and 1350℃ in Fe-Cr-Alalloys with the addition of 0.5% Y or 0.15% (La+Ce) has been studied by usingthe internal standard method of X-ray diffraction. The results indicate that theoxide scales have residual compressive stresses and the rare earth elements showan effect on them. The residual compressive stresses in alloys free from rare earthelements are less than 100 kgf/mm~2, in alloys with La and Ce, more than 200kgf/mm~2, and in alloys with Y, more than 300 kgf/mm~2. It is obvious that theadherence of oxide scale is influenced by the value of residual compressive stress. According to the experiments result of Mar, it is thought that the spalling(residual stress) of oxide scale is related to its preferred orientation. In. order toprove this relationship, a texture parameter [P]_A showing the degree of preferredorientation of α-Al_?O_3 scale is defined as follows:[P]_A=P_(0001)+P_(0118)+P_(1129)+P_(10110)P_(hkil) is the texture parameter of inverse pole-figure of α-Al_2O_3 within a strongpole range of 20°. It has been found that the adherence of oxide scale is bad at[P]<6.5 and good at [P]_A>6.5, and the rare earth elements improve the adher-ence of oxide scale through their effect in increasing the degree of preferredorientation of the oxide scale.
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