Transient liquid phase bonding assisted spark plasma sintering of La-Fe-Si magnetocaloric bulk materials

The poor mechanical properties of La-Fe-Si based alloys restrict the potential of these magnetocaloric materials. Hence, a novel transient liquid phase bonding (TLPB) processing technique was deployed during spark plasma sintering (SPS) of La-Fe-Si based bulk materials. A series of binder-free LaFe11.8Si1.2 bulk materials were prepared by SPS and hot-pressing sintering (HPS). Transient melting, which occurred during SPS, accelerated the decomposition of the 1:13 phase, resulting in low porosity and high strength. Compared to HPS samples, SPS samples have significantly larger maximum compressive strength (sigma(bc))(max) of similar to 637.9 MPa at a strain of 4.7%, good thermal conductivity of similar to 7.6 W center dot m(-1)center dot K-1 at 300 K, and a large (-Delta S-M)(max) value of similar to 11.7 J center dot kg(-1)center dot K-1 at T-C= 193 K under a magnetic field change of 0 - 5 T. Thus, binder-free La-Fe-Si based bulk magnetocaloric materials with an excellent property set have been successfully prepared by TLPB assisted SPS technology.

Automated summary

A novel transient liquid phase bonding (TLPB) technique was used to prepare binder-free La-Fe-Si based bulk materials by spark plasma sintering (SPS). Compared to hot-pressing sintering (HPS) samples, the SPS samples exhibited significantly higher maximum compressive strength (sigma(bc))(max) of about 637.9 MPa at a strain of 4.7%, good thermal conductivity of about 7.6 W·m(-1)·K(-1) at 300 K, and a large (-Delta S-M)(max) value of about 11.7 J·kg(-1)·K(-1) at Tc=193 K under a magnetic field change of 0 - 5 T. Thus, binder-free La-Fe-Si based bulk magnetocaloric materials with excellent properties were successfully prepared by TLPB assisted SPS technology.