Microstructure and giant baro-caloric effect induced by low pressure in Heusler Co_(51)Fe_(1)V_(33)Ga_(15) alloy undergoing martensitic transformation

Solid-state refrigeration based on the magneto-or mechano-caloric effect,including elasto-and barocaloric in ferroic phase transition materials is promising to replace the current vapor compression refrigeration in consideration of environmental-friendliness and energy-saving.However,both high driven field and small thermal changes in all of these caloric materials hinder the development of solid-state refrigeration.Here we report a giant baro-caloric effect near room temperature induced by a low hydrostatic pressure in Co-based Co_(51)Fe_(1) V_(33)Ga_(15) Heusler alloy.The maximum adiabatic temperature change under the applied pressure change ofΔp=0.1-100 MPa can be as high asΔ_(Tad)^(Max)=7.7 K(Δ_(Tad)^(Max)/Δpreaches up to~7.7 K kbar-1),surpassing theΔ_(Tad)^(Max)/Δpvalue reported hitherto in baro-caloric alloys.In addition,the microstructure is also studied by using the electron microscopes.Along with the austenite and martensite,the submicron V-rich particles are precipitated in this alloy,which are believed to account for enhancing mechanical properties.

Deformation behaviors of as-built and hot isostatically pressed Ti-6Al-4V alloys fabricated via electron beam rapid manufacturing

The deformation behavior of as-built and hot isostatically pressed(HIP)Ti-6Al-4V alloys fabricated using electron beam rapid manufacturing(EBRM)were investigated in this work.The deformation characteristics were characterized using a laser scanning confocal microscope and electron back-scattered diffraction(EBSD).In the as-built sample,prismatic slip was the main mode of deformation,as well as a small amount of basal slip and cross-slip.Some planar slip lines with large length scales were observed across severalαlamellae.After hot isostatical pressing,prismatic and basal slip were the main mode of deformation,accompanied by abundant cross-slip and multiple slip,and most of the slip lines were blocked within an a lamellae.These differences in deformation behavior were associated with the coarsening of a laths and the more retained p phase after HIP compared to the as-built alloy.More cross-slip and multiple slip can lead to superior elongation-to-failure and a greater strain hardening effect in the HIP alloy compared to the as-built sample.