Development of iron-based composite materials through electromagnetic radiations in a domestic microwave oven

Abstract

Microwave hybrid heating, a novel technique, is used to develop iron-based alloy (SS316), SS316+10EWAC1004 (nickel-based), and SS316+10EWAC1004+5Cr7C3 composite castings. The domestic microwave having a frequency of 2.45 × 103 MHz and a power of 0.9 kW, is used with a variable exposure time of microwave radiations. The microwave interaction procedure with the metallic powder is discussed to optimize the exposure time and temperature. A microstructure study of developed castings revealed the uniform melting of matrix and EWAC1004 with an identical dispersion of Cr7C3. The X-ray diffraction results revealed various intermetallic (Ni3Fe, Ni2Si, Cr2Ni3, MoNi4, Fe3Si, Fe2Si, CrFeNi) and hard carbides (Fe3C, Cr3C2, Cr23C6) phases. The maximum average micro-hardness is for the SS316+10EWAC1004+5Cr7C3 composite, followed by SS316+10EWAC1004. The established composite casting had a hardness of around 2 times that of the commercial SS316. The maximum density of 97% was found for Iron-based SS316-based. The grain size of microwave-processed SS316, SS316+10EWAC, and SS316+10EWAC +5Cr7C3 specimens is found to be 21 ± 4 µm, 18 ± 3 µm, and 17 ± 2 µm, respectively. It has been observed that reinforced phases hinder grain growth, and hence grain size reduces significantly. In comparison, commercial SS316 had a grain size of 31 ± 6 µm. The ASTM B-276 standard is used to determine pores that are of the order of 1.98%.