Microstructure And Properties Of Zr-ti Alloy By Liquid Phase Spark Sintering Of Zr-Ti Alloy Powder Using GH4169 Powder As Auxiliary Agent

Zirconium-Titanium alloy is one of the most widely superalloys used in aerospace and other fields at present.It has good dimensional stability,high accuracy,high temperature strength and stiffness.Zr-Ti alloy with GH4169 alloy powder as additive was prepared by spark plasma sintering,and its structure and properties were studied.The addition of GH4169 alloy powder can reduce sintering melting point,realize liquid phase sintering,save energy,refine grain size and improve the comprehensive mechanical properties of Zr-Ti alloy.At the same time,the material obtained by liquid phase sintering has good high temperature plasticity,which can realize the plastic forming of complex shape products and make it more widely used in the field of aerospace parts manufacturing.The alloys were respectively prepared by spark plasma sintering at 1273 K,1373 K and 1573 K.The curves of sintering temperature and current varying with time were obtained,and the results of sintering were analyzed.The maximum current of sintering process was between 2600 A and 3100 A.By using Mark finite element software,the thermal,electrical and mechanical coupling simulation of sintering process of alloy powder was carried out under the conditions of 1273 K,1373K and 1573 K,respectively.The temperature and relative density distributions of sintering die,initial stage of heat preservation and end stage of heat preservation of alloy material were studied,and distribution curves of temperature and relative density in the axial and radial directions are obtained and their distribution laws are analyzed.In the initial stage of sintering and holding,the temperature varies greatly and the sample is not fully compact.At the end of sintering,the temperature difference is small,the temperature distribution is more uniform and the relative density is increased.The maximum relative density of 1273 K,1373K and 1573 K is 98.18%,99.28% and 99.45%,respectively.At 1273 K,the structure of the alloy sample is a mixture of ? and ? phases,and there are a few fine ? phases in the grains,while the titanium content of the alloy material obtained by No.1 ratio is 62%,so there is an oxide Ti3 O besides the ? and ? phases;the Zr zirconium content of the alloy material obtained by No.2 ratio is 47%,Therefore,in addition to the ? and ? phases,there is also an intermetallic compound ZrMoCr.A large number of fine ? phases are gradually precipitated in the grains at 1373 K,and the alloys at 1573 K contain not only ? and ? phases,but also ? phase.But ? phases have grown up one by one,and the grain boundary morphology of equiaxed ? phase grains is very unclear.The microhardness observation of Zr-Ti alloy shows that the hardness of amorphous part is the highest,followed by grain boundary hardness,and the hardness of grain position is the lowest.With the increase of temperature,the hardness of intra-grain and amorphous parts increases gradually,the hardness of amorphous parts is between 600-690 HV and that of crystalline parts is between 520-580 HV.