For additive manufacturing such as laser powder bed fusion (LPBF), commercial aluminum alloy (AA) 6061 is typically considered unsuitable due to formation of solidification cracking and/or excessive porosity. In this study, to improve buildability/printability of AA6061, 1 wt% of Zr was alloyed to produce Zr-modified AA6061 by LPBF. Powders of unmodified and Zr-modified AA6061 were produced by gas atomization, and utilized as a feed-stock for the LPBF to fabricate specimens for microstructural examination and mechanical testing. The as-built unmodified AA6061 exhibited poor printability due to formation of cracks and porosity in the microstructure regardless of LPBF parameters. However, the Zr-modified AA6061 exhibited near full density, with substantial reduction in porosities without any solidification crack for a certain LPBF processing window. The improved printability of Zr-modified AA6061 was attributed to a significant grain refinement, which would reduce the solidification cracking susceptibility by hampering the epitaxial growth of long columnar cracks, as observed in unmodified AA6061. Yield strength, tensile strength and strain-at-failure for the as-built Zr-modified AA6061 were determined to be 210 MPa, 268 MPa, and 26.5%, respectively. These are superior to the tensile properties of AA6061 in O-annealed condition or in as-cast condition. After T6 heat treatment, yield strength, tensile strength and strain-at-failure of Zr-modified AA6061 were determined to be 300 MPa, 327 MPa, and 14%, which were again superior to the tensile properties of wrought AA6061 in T6 heat treated condition. Effects of Zr addition on the buildability/printability improvement and mechanical properties of AA6061 were corroborated by a variety of electron microscopic characterization.

对于诸如激光粉末床熔合（LPBF）的增材制造，由于形成的凝固裂纹和/或过多的孔隙率，通常认为商用铝合金（AA）6061不适合。在这项研究中，为了提高AA6061的可建造性/可印刷性，将1 wt％的Zr合金化以通过LPBF生产Zr改性的AA6061。未改性和Zr改性的AA6061的粉末通过气体雾化生产，并用作LPBF的原料，以制备用于微结构检查和机械测试的样品。不论LPBF参数如何，由于在微观结构中形成裂纹和孔隙，未加工的AA6061制成品的可印刷性较差。但是，Zr修饰的AA6061表现出接近全密度，对于一定的LPBF处理窗口，孔隙率显着降低，而没有任何固化裂纹。Zr改性AA6061的可印刷性得到改善，这归因于显着的晶粒细化，这将通过阻碍长柱状裂纹的外延生长来降低凝固裂纹敏感性，如在未改性AA6061中观察到的那样。测得的Zr改性AA6061的屈服强度，抗拉强度和破坏应变分别为210 MPa，268 MPa和26.5％。这些在O退火条件或铸态条件下均优于AA6061的拉伸性能。经过T6热处理后，测得Zr改性AA6061的屈服强度，抗拉强度和断裂应变分别为300 MPa，327 MPa和14％，再次优于经过T6热处理的锻造AA6061的拉伸性能。状况。