1. 晶粒（crystalline grain）、晶界（grain boundary）
組成金屬(shu)材(cai)料的小晶(jing)體(ti)，稱(cheng)為(wei)晶(jing)粒。晶(jing)粒與晶(jing)粒之間(jian)的分界(jie)(jie)面，稱(cheng)為(wei)晶(jing)界(jie)(jie)。
2. 相（phase）、相界（phase boundary）
在金(jin)屬或合(he)金(jin)中(zhong)，凡成分相(xiang)同、結構(gou)相(xiang)同并有(you)界(jie)(jie)面(mian)互相(xiang)隔開的均勻組成部分，稱(cheng)為相(xiang)，相(xiang)與相(xiang)之間的界(jie)(jie)面(mian)，稱(cheng)為相(xiang)界(jie)(jie)。
3. 固溶體（solid solution）
組成合(he)金的(de)(de)一種金屬(shu)元(yuan)素的(de)(de)晶(jing)體(ti)中溶(rong)有另一種元(yuan)素的(de)(de)原(yuan)子(zi)形成的(de)(de)固(gu)態(tai)相，稱(cheng)為固(gu)溶(rong)體(ti)。固(gu)溶(rong)體(ti)一般有較高的(de)(de)強度、良好的(de)(de)塑性(xing)(xing)、耐蝕性(xing)(xing)以及高的(de)(de)電阻和磁性(xing)(xing)。
按溶質原(yuan)子(zi)在晶格中的位置不同可分為置換固溶體和間隙固溶體。
①. 置換(huan)(huan)固(gu)(gu)溶(rong)(rong)體(ti)：溶(rong)(rong)質原(yuan)子占據溶(rong)(rong)劑晶格(ge)中的結點(dian)位(wei)置而形(xing)成的固(gu)(gu)溶(rong)(rong)體(ti)稱置換(huan)(huan)固(gu)(gu)溶(rong)(rong)體(ti)。當(dang)溶(rong)(rong)劑和溶(rong)(rong)質原(yuan)子直徑相差不大，一般在15％以內時，易(yi)于形(xing)成置換(huan)(huan)固(gu)(gu)溶(rong)(rong)體(ti)。銅(tong)鎳二元(yuan)合金即形(xing)成置換(huan)(huan)固(gu)(gu)溶(rong)(rong)體(ti)，鎳原(yuan)子可在銅(tong)晶格(ge)的任意位(wei)置替(ti)代銅(tong)原(yuan)子。
②. 間(jian)隙(xi)固(gu)(gu)溶(rong)(rong)(rong)(rong)體(ti)(ti)(ti)：溶(rong)(rong)(rong)(rong)質(zhi)(zhi)原(yuan)子(zi)分(fen)布于溶(rong)(rong)(rong)(rong)劑晶格間(jian)隙(xi)而形成(cheng)的固(gu)(gu)溶(rong)(rong)(rong)(rong)體(ti)(ti)(ti)稱(cheng)間(jian)隙(xi)固(gu)(gu)溶(rong)(rong)(rong)(rong)體(ti)(ti)(ti)。間(jian)隙(xi)固(gu)(gu)溶(rong)(rong)(rong)(rong)體(ti)(ti)(ti)的溶(rong)(rong)(rong)(rong)劑是(shi)直徑較大(da)的過渡族金屬，而溶(rong)(rong)(rong)(rong)質(zhi)(zhi)是(shi)直徑很(hen)小的碳(tan)、氫等非金屬元(yuan)素。其形成(cheng)條件是(shi)溶(rong)(rong)(rong)(rong)質(zhi)(zhi)原(yuan)子(zi)與溶(rong)(rong)(rong)(rong)劑原(yuan)子(zi)直徑之比必須小于0.59。如鐵(tie)(tie)碳(tan)合(he)金中，鐵(tie)(tie)和碳(tan)所形成(cheng)的固(gu)(gu)溶(rong)(rong)(rong)(rong)體(ti)(ti)(ti)-鐵(tie)(tie)素體(ti)(ti)(ti)和奧氏體(ti)(ti)(ti)，皆為(wei)間(jian)隙(xi)固(gu)(gu)溶(rong)(rong)(rong)(rong)體(ti)(ti)(ti)。
按固(gu)(gu)溶(rong)度來分(fen)類，可分(fen)為有限固(gu)(gu)溶(rong)體(ti)(ti)和(he)無限固(gu)(gu)溶(rong)體(ti)(ti)。無限固(gu)(gu)溶(rong)體(ti)(ti)只(zhi)可能是置換固(gu)(gu)溶(rong)體(ti)(ti)。
按(an)溶(rong)(rong)質原子(zi)(zi)與溶(rong)(rong)劑原子(zi)(zi)的相對(dui)分布(bu)來分，可分為無序(xu)(xu)固溶(rong)(rong)體(ti)和有序(xu)(xu)固溶(rong)(rong)體(ti)。
4. 金屬化合物（metal compounds）
合(he)(he)金(jin)中(zhong)不(bu)同(tong)元素(su)的(de)原子相(xiang)互作用(yong)形成(cheng)的(de)、晶格(ge)類(lei)型和(he)性能都完全(quan)不(bu)同(tong)于其組成(cheng)元素(su)的(de)，具有(you)金(jin)屬(shu)(shu)特性的(de)固態相(xiang)，稱為金(jin)屬(shu)(shu)化(hua)合(he)(he)物(wu)(wu)。金(jin)屬(shu)(shu)化(hua)合(he)(he)物(wu)(wu)多數(shu)具有(you)熔(rong)點(dian)高、硬(ying)而脆(cui)的(de)特點(dian)，是(shi)合(he)(he)金(jin)中(zhong)很重要的(de)強化(hua)相(xiang)。
