激光熔覆制备Fe-Al金属间化合物覆层

分别以纯Fe3Al粉、铁基合金粉 铝粉为原料,采用激光熔覆工艺在钢基体表面制备Fe-Al金属间化合物.利用扫描电镜、能谱仪与X射线衍射等方法对熔覆合金层以及与钢基体的结合界面等进行了显微组织与相结构的分析.结果表明,采用这两种原料均可以获得与基体之间良好冶金结合的Fe-Al合金覆层,覆层组织致密,均与基体实现了良好的冶金结合;直接熔覆Fe3Al工艺的覆层存在裂纹现象,而铁基合金粉 铝粉反应合成工艺的覆层组织含少量孤立微孔隙,但无裂纹缺陷;直接熔覆Fe3Al的覆层组织由粗大的等轴状晶团构成,等轴状晶团内部及晶界由大量极细小的板条状Fe3Al晶粒构成,许多相邻板条晶之间具有一致的晶体取向;反应合成工艺的覆层组织主要由大量细密、均匀的树枝晶构成,树枝晶所含元素的原子比Fe:Al:Ni:Cr:Si大约为55:24:8:8:5.

Preparation of deposited coating of Fe-Al inter metallic compound by laser cladding

Two kinds of Fe-Al intermetallic coatings were prepared on steel substrate by laser cladding with powders of Fe₃Al and mixed powders of Fe-based alloy and Al.The microstructure and phase constitution of the coating and the interface between coating and subsurate were studied with SEM,EDX and X-ray analysis.Coatings jointed metallurgically with the substrate were obtained with both methods,and cracks were found in the cladding with powders of Fe₃Al and a few pores were found in the synthesize cladding of mixed powders of Fe-based alloy and Al,but no cracks were found in the latter.Cladding microstructure of the former consisted of coarse equiaxed grain groups,which consisted of a large amount of banding fine Fe₃Al grains and some neighbouring banding grains have the similar orientation.The cladding microstructure of the latter consists mainly of uniform and fine dendrites,in which the atom ratio of Fe:Al:Ni:Cr:Si is about 55:24:8:8:5.