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用非自耗电弧炉熔炼制备了La(Fe11.05Co0.85S i1.1)B0.25铸锭,并将该铸锭在氩气保护中球磨制粉,采用SPS(放电等离子烧结技术Spark P lasma S intering)将该粉制成La(Fe11.05Co0.85S i1.1)B0.25合金,在高温(1070℃)下对其进行20 h热处理;空冷之后用XRD及SEM检测了铸锭热处理样品、SPS烧结样品及SPS热处理后样品的相及组织结构,利用VSM和磁热效应直接测量仪测量了这3种状态下合金的等温磁熵变和绝热温变。结果表明,铸锭合金的基相组织结构中晶粒大小规则较均匀,晶界清晰明显,在0~1.5 T的变化磁场下测得其等温磁熵变达到-5.22.J(k.gK)-1,绝热温变也达到2.3 K,而采用SPS技术制得的样品的基相组织结构中没有明显晶界且夹杂较多,其等温磁熵变为-3.90.J(k.gK)-1,绝热温变为1.9 K(0~1.5 T);经过热处理的SPS样品基相组织结构中,有少量晶界形成,但晶粒大小不规则,测得其等温磁熵变为-3.72.J(k.gK)-1,绝热温变为1.5 K(0~1.5 T);与铸锭相比较,SPS技术制得的合金样品和经过高温热处理之后的SPS样品的绝热温变值和等温熵磁变值均降低,同比之下这两种样品较铸锭样品的居里点和半峰宽却发生了改变,均显著提高;可以看出采用SPS技术制备的室温磁制冷材料La(Fe11.05Co0.85S i1.1)B0.25能够在较宽的温度范围内制冷,但其磁热效应却相对降低。
La (Fe11.05Co0.85Si1.1) B0.25 ingot was prepared by non-consumable electric arc furnace. The ingot was ball-milled by argon gas protection. Spark (SPS) lasma S intering, La (Fe11.05Co0.85S i1.1) B0.25 alloy was prepared and subjected to heat treatment at high temperature (1070 ℃) for 20 h. After air cooling, the ingot heat treatment The phase and microstructure of samples after SPS sintering and SPS heat treatment were measured. The isothermal magnetic entropy change and adiabatic temperature change of the alloys were measured by VSM and magnetocaloric effect direct measuring instrument. The results show that the grain size of the ingot alloy is uniform and the grain boundaries are clear and clear. The isothermal magnetic entropy change reaches -5.22J (k.gK) under the changing magnetic field of 0 ~ 1.5 T, -1, and the adiabatic temperature change reached 2.3 K. However, the microstructure of the samples prepared by SPS technique did not show obvious grain boundaries and inclusions, and the isothermal magnetic entropy changed to -3.90. J (k.gK) - 1, and the adiabatic temperature was changed to 1.9 K (0-1.5 T). The microstructure of SPS samples after heat treatment showed a small amount of grain boundaries, but the grain size was irregular. The isothermal magnetic entropy changed to -3.72. J (k.gK) -1, and the adiabatic temperature changed to 1.5 K (0-1.5 T). Compared with the ingot, the adiabatic temperature change and the isothermal temperature of the alloy prepared by the SPS technique and the SPS sample after the high temperature heat treatment Entropy magnetic susceptibility values are lower, compared with the same time, the two samples Curie point and half-width of the ingot samples have changed, were significantly improved; can be seen using SPS technology room temperature magnetic refrigeration material La (Fe11 .05Co0.85S i1.1) B0.25 can be cooled over a wide temperature range, but its magnetocaloric effect is relatively reduced.