Research On Thermoplastic Amorphous Alloy Microfluidic Chip Mold And Its Performance

In this paper,(Zr_0.6336Cu_0.1452Ni_0.1012Al_0.12)_99.4Y_0.6 amorphous alloy was selected as the research object.The high and low temperature mechanical properties test system was used to prepare amorphous alloy microfluidic chip stamping mold under different process parameters.X-ray diffractometer（XRD）,scanning electron microscope（SEM）and laser confocal microscope（CLSM）were used to study the microstructure and molding quality of the samples.The mechanical properties and corrosion resistance of molded samples were analyzed by microhardness tester and electrochemical workstation.Meanwhile,based on our previous research,the constitutive model of(Zr_0.6336Cu_0.1452Ni_0.1012Al_0.12)_99.4Y_0.6 amorphous alloy was calculated,the commercial software Deform were used to simulate the metal forming process,and the rheological filling process in the micro channel was further studied.Secondly,PMMA was stamped by using amorphous alloy die,and the effect of process parameters on forming quality was studied.Moreover,the amorphous mold is crystallized to obtain high temperature stability,and the glass material with high softening temperature is imprinted to prepare glass microfluidic ch ip,which is tried to be applied to the field of high temperature mold.The following conclusions were obtained.（1）The results show that the samples formed at 683 K and 703 K remain amorphous,while the samples formed at 723 K all undergo different degre es of crystallization,and the degree of crystallization is inversely proportional to the strain rate.What’s more,the parameters of molding process have a great influence on the quality of the formed samples.The filling height is proportional to the tem perature and load,and is inversely proportional to the strain rate,but excessive temperature will lead to crystallization of the alloy.The amorphous alloy micromold is prepared with the process parameters of T=703 K,（?）=1×10^-3 s^-1and P=1500 N,and the surface embossed pattern is clear and the roughness is close to th at of the microchannel parent mold.It was found that the hardness distribution in the formed area was uniform,and the average hardness reaches 473.4 HV,which is slightly higher than 467.3 HV in the unformed area.The main reason was the cooling rate and the change of free volume.In addition,the corrosion properties of the amorphous mold,as-cast alloy and common mold core materials were tested.It is found that the amorphous mold has excellent corrosion properties,and the corrosion current density reache s 10^-8 A·cm^-2in 1 mol/L HCl solution.（2）The constitutive model of amorphous alloy used in the experiment has high accuracy.Deform software was used to simulate the filling process of the alloy microchannel.It is found that the closer to the center of the channe l,the higher the flow velocity.The closer to the alloy matrix,the more uneven the flow velocity distribution.The position is close to the flow front,the overall flow velocity distribution of the alloy gradually becomes gentle.Meanwhile,it is found that the effective strain distribution is different at different strain rates.When the strain rate is low,the effective strain distribution tends to an interval,and the distri bution is more uniform.The alloy deformation has better fluidity and simple flow behavior,which is more conducive to thermoplastic forming.When the strain rate is high,the effective strain distribution is dispersed,and the strain difference is not con ducive to thermoplastic molding.The simulation results correspond to the actual experimental results.（3）When the microfluidic chip is prepared by using amorphous alloy imprinting PMMA,it is found that the molding quality is affected by temperature and press stroke.The higher the temperature is and the longer the press stroke is,the better the press quality is.Moreover,the surface hardness of the micromold increased greatly after high temperature crystallization,which is mainly caused by the generation of crystalline phase and the annihilation of free volume.The glass with highe r softening temperature point is embossed by the micromold after crystallization,the microchannel is successfully embossed on the surface of the glass,and the depth of the channel is close to the expectation.This method combines the processing advantages of superplastic forming in the supercooled liquid region of amorphous alloy with the high temperature stability of crystalline metal,which verifies the possibility of amorphous alloy as a high temperature mold.