| TiAl alloys due to their low density, high temperature strength, high oxidation resistance etc. are considered as a new generation of alloys for high temperature structural materials in aerospace industries. The TiAl alloys not only can be directly used as structural materials but also have extremely promising aerospace applications. However, the common challenges for further applications of TiAl alloys are the low ductility and toughness at room temperature as well as the poor hot workability. Its mechanical property can be expected to be improved by adding Ti alloys due to the Ti-6Al-4V alloy have better ductility and toughness at room temperature than TiAl alloys. In this paper, the laminated composite sheets of Ti-43Al-9V-0.3Y/Ti-6Al-4V and Ti-44Al-8Nb-0.2W-0.2B-Y/Ti-6Al-4V with Ti alloys overlapped with TiAl alloys were fabricated hot pack rolling, namely the TiAl/Ti/TiAl and TiAl/Ti/TiAl/Ti/TiAl alloys. The phase composition and the mechanical properties of the as-rolled laminated composite alloys have been discussed.The results prove that with the increase of layers, the volume fraction of interface increase but the volume fraction of Ti-6Al-4V alloys decrease. The interface layer of the two kinds TiAl/Ti alloys can be divided into four regions including α+β, α/α2+β0/β, α/α2+γ+β0/β, γ+β0 for Ti-43Al-9V-0.3Y/Ti-6Al-4V with the mean size of 8.55 um. The content of α/α2 phases, β/β0 phases, and γ phases are 64.4%, 21.3%, and14.3%, respectively. And the Ti-44Al-8Nb-0.2W-0.2B-Y/Ti-6Al-4V alloys are consisted of α+β, α/α2+β0/β, α/α2+γ+O+β0/β, α2+γ+β0 regions with 72.4% α/α2 phases, 8.9% β/β0 phases, 17.5% γ phases and 1.2% O phases. And its average grain size is 2.56 um.The results can be obtained by analyzing the micro-hardness, bending tests, tensile experiments of the laminated composite sheet. The β/β0 region has the highest microhardness and its hardness is, followed by α2-Ti3 Al phase and γ phases. On the whole, the bending strength, fracture toughness and tensile strength of both the TiAl/Ti alloys with three layers are higher than five layers at room temperature. At 800℃, the TiAl/Ti alloys with five layers has better elongation than the three layers with the similar tensile strength.The bending strength of Ti-43Al-9V-0.3Y/Ti-6Al-4V with three layers is 1500.06 MPa and its fracture toughness is 38.35MPa·m1/2 which is the 1.55 times of Ti-43Al-9V-0.3Y alloys. The tensile strength of the three layers sheet is 698.94 MPa at room temperature and At 800 °C tensile strength is 303.18 MPa with 21.46% ductility.The overall mechanical property of Ti-44Al-8Nb-0.2W-0.2B-Y/Ti-6Al-4V alloys with three layers are improved compared with the Ti-43Al-9V-0.3Y/Ti-6Al-4V alloys. The specific properties are as followed. The bending strength, fracture toughness, tensile strength are 2001.68 MPa, 44.50MPa·m1/2, and 530.88 MPa, respectively. And The fracture toughness is as 3.4 times as the Ti-44Al-8Nb-0.2W-0.2B-Y alloys. At 800°C,The tensile strength is as high as 495.94 MPa with the elongation of 9.49%. |
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