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热压烧结参数对Ti35421组织与力学性能的影响

Effect of hot press sintering parameters on microstructure and mechanical properties of Ti35421

  • 摘要: 采用热压烧结法制备了Ti‒3Al‒5Mo‒4Cr‒2Zr‒1Fe(Ti-35421,质量分数)合金,通过正交实验探究了烧结温度、烧结压力和保温时间对Ti-35421合金组织形貌和力学性能的影响,并对相对密度、次生α相尺寸、硬度以及压缩性能进行表征。结果表明:烧结温度是影响Ti-35421合金性能的最主要参数,随着烧结温度的升高,合金的屈服强度先增大后减小,断裂应变先减小后趋于稳定;过高的烧结温度会导致晶粒长大,进而降低合金压缩性能。最佳烧结参数为烧结温度900 ℃、烧结压力45 MPa、烧结时间2 h,该条件下制备的合金屈服强度达到1248 MPa,断裂应变为23.03%。热压烧结得到的Ti-35421合金样品主要由原始β晶粒以及晶内的次生α相组成。随着烧结温度的升高,β晶粒在烧结体中的尺寸显著增大,而次生α相的长宽比也增大。

     

    Abstract: The Ti‒3Al‒5Mo‒4Cr‒2Zr‒1Fe (Ti-35421, mass fraction) titanium alloys were prepared by hot pressing sintering in this paper. The influences of sintering temperature, sintering pressure, and holding time on the microstructure and mechanical properties of Ti-35421 alloys were explored by orthogonal experiments and characterized by relative density, secondary α phase dimension, hardness, and compression properties. The results show that the sintering temperature is the most important parameter affecting the properties of Ti-35421 alloys. As the sintering temperature increases, the yield strength first increases and then decreases, the fracture strain first decreases and then becomes stable. At the same time, the high sintering temperature causes the grain growth, which reduces the compressive properties of the Ti-35421 alloys. The optimal sintering parameters are followed as the temperature of 900 ℃, the sintering pressure of 45 MPa, and the sintering time of 2 h, and the corresponding yield strength and fracture strain of the Ti-35421 alloys reach 1248 MPa and 23.03%, respectively. The Ti-35421 alloys obtained by hot pressing sintering are mainly composed of the original β grains and secondary α phase within the grains. As the sintering temperature increases, the size of β grains in the sintered body increases significantly, and the aspect ratio of the secondary α phase also increases.

     

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